In Islam, dunyā (Arabic: دُنْيا) refers to the temporal world and its earthly concerns and possessions, as opposed to the hereafter (ʾākhirah). In the Qur'an, dunyā and ākhira are sometimes used dichotomously, other times complementarily. Islam does not a priori dismiss the world as "evil".
Barzakh is the world after this world which starts from death and goes on till the day of Judgment. It is mentioned in Quran (There is a Barzakh after their death till the day of they will be resurrected) (Sura 23, Verse 100).
Barzakh includes the grave but it is wider than the grave. Grave starts on burial but Barzakh starts on death which is before burial.
The pious believer's grave is a garden from the Paradise while the grave of the disbeliever is a ditch from the hellfire, as the Hadeeth states.
I agree with the viewpoint that you said regarding Imam Ali (A) loving his wife greatly, and it seems that the Prophet (S) and his family had very open hearts, and also that love for their families was part of their spirituality and perfection. So I would not say that, in the tradition ascribed to them (A), there is an ideal of cutting of love for one's wife and children.
As I am sure you know, there some clear narrations on this topic attributed to the Prophet (S) such as "I was made to love three things - perfume, women, and prayer", and as related from Imam Kazim (A) "whenever a man's faith increases, his love of women increases." Of course this should not be a haraam love whereby one does illict acts in the name of love, but, rather, the capacity for love and connection with and appreciation of the opposite gender increases, perhaps as part of spiritual growth. It is not a sign of spiritual growth to be cold and standoffish with one's lawful spouse (unless there are serious marital or personal problems that cause that, unrelated to this subject).
Of course, there are many approaches to mysticism and gnosis, and sometimes people prescribe other approaches according to their understanding for their own reasons even if the are somewhat different from the above.
However, perhaps one can glean from the Qur'an and hadith that (a) although it is good to be open to one's spouse and children and love them, one should not grow overattached to them to the point where they place them above Allah, whatever that means to a person in practice, (b) one should not be attached to the worldly life, although one can take comfort in the knowledge that human relationships can outlast the worldly life, and (c) sometimes we are tested by these things, and we are also tested by what we love most. For some people, their greatest tests in life relate to their family or children. Inshallah you will be protected from this.
In my view - and this is just my view, it may irk others - in some Muslim spiritual circles there is a sort of cynicism when it comes to human love, and an emphasis that this world is just for tasting the delights of Allah or the hereafter, and we should not dwell on these things or expect to have them. I have often suspected that this may be rooted in some of the social restrictions and disappointments relating to worldly life that some people have had, especially in the older generations - for instance, feeling compelled to marry someone who one didn't really want to be with, or other such problems. And to some degree, a way to deal with this is to look to what is beyond this world spiritually and not focus on it. I am not saying this is the situation with everyone but perhaps it is a factor.
Those believers who repent doing wrong, and sincerely seek forgiveness, after giving back the right of others, should not be punished neither in the Day of Judgement nor in Barzakh , after they have been forgiven by Allah (SWT).
The Qur'an and hadith (both Sunni and Shi'i) give the sense that the jinn exist in the same world as us. The Qur'an and hadith describe occasional interactions between humans and jinn on a physical level - for instance, seeing a jinn manifest as an animal (as in the story of the jinn who came to see Imam Ali in the Mosque of Kufa) or hearing their voices audibly. Another example would be the jinn working for the prophet Sulayman (A).
However, apart from those occasional interactions, usually jinn keep to themselves and human beings do not see them.
However, some mystics have held that there is a sort of veil between the human world and the jinn world, which you could call the barzakh. That is, humans and jinn subsist in the same realm, but in something akin to parallel dimensions. I am not aware of any basis for this in Qur'an and hadith, but it could be true.
So do jinn live in the barzakh? To me, the best view is "maybe" and "it depends on what you call the barzakh". If one takes "barzakh" to mean something akin to "mundus imaginalis" - that is, the imaginal realm which humans access through dreams, visions, or imagination, it might be correct to say that jinn live in barzakh. After all, people usually encounter jinn in dreams or the inner realm (for instance, Shaytan whispering to the heart), rather than in physical life. This is similar to how people are more likely to have a dream or vision of a deceased person, such as Imam Husayn (A), rather than physically seeing them walking down the street.
If one takes barzakh to mean specifically the place where human spirits go after death but before the Resurrection... while this meaning of "barzakh" may have some relationship to the above, I am not aware of any texts which specifically say that deceased human spirits live in the same place as living/deceased jinn, although I don't think we have any texts that rule out any sort of interaction ever between living/deceased jinn and deceased humans.
In any case, it seems as if the existence of the human being after death is more similar to the jinn, because the human being in the barzakh is less encumbered by the physical body and able to move around more.
In fact, I don't think we have any texts that say what happens to jinn after they die but before the Resurrection - for instance, do they go to their own barzakh? - however, the Qur'an says that, after Resurrection and Judgment, the jinn who go to Hell and the humans who go to Hell are all mixed together in the same Hell. It does not specify whether the jinn who go to Heaven and the humans who go to Heaven go to the same Heaven.
Anyway, it can be quite difficult to make concrete statements about spiritual cosmology, metaphysical realities, or other things which are not tangible. Even if someone says something, it is really quite difficult to prove whether it is true or false, except in the case of Qur'an and accurate hadith, which we accept on the basis of them being divinely inspired or approved.
So, this, in short, is my understanding of what the Qur'an and hadith say, and also what some mystically inclined thinkers have said. God knows best!
Jinn have their own world and we are not supposed to deal with them nor are we responsible about anything in their world. Those humans who seek help from Jinn will suffer more.
Hadeeth says: The deceased is too far away from the living person, while the living person is too near to follow the deceased.
Departed souls are in the hands of Allah (Allah takes back the souls on death)(Sura 39, Verse 42). Meeting the souls of the deceased in dream is in the hands of Allah (SWT).
We can enjoy the permissible worldy pleasures while staying in the boundaries of Islam.
It is stated in the Hadeeths that husband and wife who enter Paradise will be completely transformed in Paradise and will be be the best for one another. All negative points will be removed away and every thing they wish in the other will be granted. The wife will be more beautiful in her husband's eyes than the Hoor, and the husband will be the best man in his wife's eyes.
It is good to pray to Allah (SWT) to grant you the best with out suggesting on Him. Allah knows the best and He grants the best to His sincere servants.
Yes it is permissible and very good.
We are been encouraged to seek from Allah (SWT) every wish we need or want as He says in Quran إدعوني أستجب لكم (Seek from me, I will respond to you) Sura 40, verse 60. وآتاكم ٬من كل سألتموه وإن تعدوا نعمة الله لا تحصوها (And He granted you from whatever you supplicate sand if you try to count the bounties of Allah you will never count it) Sura 14, verse 34.
It is narrated that one of the first things that happens in the barzakh (the next realm after this life) is that a human being is forced to transcribe their entire life.
Also with respect to the hereafter it is said that all deeds will be clearly visible and known, and that all things are recorded (except for what Allah wills to hide or forgive).
So, basically, there is a complete memory there, including of things we have forgotten during our lives in this world.
This is one of those "yes" and "no" questions.
Yes, in the sense that God sent the Prophet Muhammad as the final prophet for all people, and the Qur'an as revelation for all people. So it is intended for all people, and all people should do what God wills, since God is the one who created us and the universe.
However, perhaps there was some divine wisdom in creating the world in such a manner that there is diversity in faith. That is, obviously, God knew when sending the Prophet (S) that not every person in the world is going to accept Islam as a faith, for whatever reason (especially human reasons like geography, culture, language, fear of what is different, etc). This is similar to how Adam and Eve shouldn't have eaten from the tree, but at the same time Allah knew that they would eat from the tree, and doing so was part of the divine plan for humanity.
Qur'an 9:33 indicates that Islam will eventually predominate, and this is expected to happen during the time of the Mahdi. However, even the, there are some hints that some people will still formally follow other religions, even though the Mahdi will settle in as a just and welcomed ruler and will have proof of the religion with him.