Qur'an

There are a few reasons, including:

* Modesty (regarding explicit subjects, the Qur'an tends to be more modest and address men specifically as well as use euphemisms, even if both men and women are intended)
* Generality (zawj/azwaj can be understood in some cases to mean "spouses" in general and not specifically "wives" as it is often translated)
* In some cases, it is specifically addressing men and speaking about women (for instance, the verse about zihar when it talks about men divorcing their wives via zihar)

So it really depends on the verse. A good resource to look at for varying interpretations of verses is _The Study Quran_ edited by S. H. Nasr.

Hope that helps!

This question has been discussed to some degree here: https://www.al-islam.org/ask/topics/7744/questions-about-Houris

Anyway, it seems that this is said in the Qur'an as a form of encouragement (just as some things about Hell can be seen as a discouragement from doing certain things). Apparently this must have been or indeed must be encourgaging to men. As for why men are addressed and promised this instead of women, some might say it is out of modesty, although I might also suggest that perhaps men need a little more encouragement sometimes! :)

As for what virginity means in the Hereafter... that is more complicated question. One would assume that the physics of things is somewhat different there, and while there is a means for 2 beings to relate which is analagous to how 2 beings relate here, it is unlikely to involve all of the specific physiological details of earthly virginity.

There is also a certain logic behind saying that the huris are "not touched by jinn or men", since (a) it is generally held that jinn have their own Paradise and so they wouldn't be interacting with them anyway, and (b) there won't be people in Paradise until the judgment, so they wouldn't have had anyone to have a relationship with before. (c) Also since there are so many of them, perhaps they are all created as exact matches (soul-mates, if you will) to their human partners and not necessarily compatible with others.

As for women, seeing as it is said that we can more or less have whatever we want in Paradise, there is no reason what women should not have virgins, if that is what they would like.

That being said, I am sure you will agree that men are the cause of 90% of headaches for women in this world, so I would not be surprised if some women decide they would like some peace and quiet instead!

(With all apologies to our male colleagues who may completely disagree :) )

Anyway, Allah speaks to us according to our understanding in this world, when it comes to matters outside of this world, there is a certain amount of guesswork or theorizing when it comes to these questions. It is however an interesting question to ponder.

Teachers are highly respected in the Islamic tradition. 

The Qur'an does not talk about teachers too much, perhaps because part of the reform that Islam was bringing was an educational reform, and so, during the time of the Prophet (S), the society was transitioning to one with more focus on learning. However, one can see all the prophets discussed in the Qur'an as teachers.

Furthermore, the Prophet (S) emphasised teaching and learning, for instance, when he freed some literate prisoners of war, rather than requesting money in exchange for returning them, he requested that they teach others to read first. Islam has been referred to as 'the world's largest literacy program' and I think that is an apt description.

Additionally, there are many mentions in hadith of the importance of teaching, necessity and value of learning, and honour of the teacher, such as:
 
* It is narrated that the Prophet (S) said, ‘The best form of charity is for a man to gain knowledge and then teach it to his fellow brethren.'

* It is narrated that Imam Ali (A) said, ‘Everything decreases with giving away except knowledge.’

* It is narrated that Imam al-Baqir (A) said, ‘For the teacher of good, all the animals on the land and the fish in the sea seek forgiveness on his behalf, as do all creatures great and small in Allah’s earth and sky.’

* It is narrated that Imam al-Sadiq (A) said, 'Everything has a zakat, and the zakat of knowledge is to teach it to those who are worthy of it.’

If you have an interest in this subject, I would recommend the following book:

Desire of the Aspirant: On the Etiquette of the Teacher and the Student
by al-Shahid al-Thani [a classical Muslim scholar of the Shi'i persuasion]
translated by Alexander Khaleeli