Grave

Yes it is permissible to construct solid grave to protect the dead body from water or any other expected harm.

Wassalam.

The results of our deeds can be in different stages starting from this life when believers who do good feel peace of mind and mental happiness, and bad doers feel depressed and unhappy. Grave us another stage where we see the results of our deeds, then the Day of Judgement.

'Wassalam.

Allah, The Exalted, Grants extra ordinary gifts to His most sincere servants to help the believers whenever and however Allah Wants them to help. The Prophet Muhammad (SAWA) and Imam Ali (AS) are the best servants of Allah (SWT) and Allah Grants them the best. Their supplications are accepted and the intercession for us is granted by Allah if we are sincere and dedicated believers. All Muslims salute the Prophet Muhammad (SAWA) in every Prayer by saying ASSALAMU Alaina Ayyuha Nabiyyu Wa Rahmatullah Wa Barakatuh. The Prophet (SAWA) replies our salutations and prays for us. Same also by Imam Ali (AS).

'Wassalam.

According to the narrations, the questioning by the two angles occurs after burial in the grave, unless the dead person has no grave because he was not buried for any reason e.g. drown in the sea or ocean or burnt in chemical or atomic or nuclear bomb and his dead body was not found, then it will happen after reasonable time after his death. 

Wassalam.

It is the same grave which the dead believer buried in. He feels and enjoys the paradise bounties even if his physical body turns to soil but he remains in his soul and spirit feels the happiness.

'Wassalam.

Barzakh is the world after this life and before the day of Qiyamah. Pious believers who avoided sinful acts will enjoy peaceful life in Barzakh and their graves will be gardens from the Paradise. Believers who did not avoid sinful acts and died before full repentance and forgiveness from their sins, will meet the results of their sins in the Brazakh, so the punishment in Barzakh for those believers who did commit many sinful acts and did not seek forgiveness till they died. It is not for all believers.

May Allah The Most Merciful and Most Compassionate Protect us from sinning and the bad consequence of sins in this life and after it in Barzakh in the Day of Judgment. 
 

Wassalaam

Every pious believer including the martyr will be dying with peace and will see Ahlul Bayt (AS) on his death, who will give him glad tidings about the Mecry of Allah for pious believers. Angles of mercy will also give the pious believer glad tidings and look after him. Martyrs never die, but remain alive in a type of life which we can not feel as Allah says in Quran (And say not of those who were killed in the Way of Allah as dead. Nay, they are living but you perceive not. (Sura 2, verse 154).

Every believer who dies on the love of Ahlul Bayt will die as a Shaheed. This is according to Hadeeth narrated from the Prophet Muhammad (SAWA) in Shia and Sunni books like

1- Tafseer Al-Zamakhshari V. 4,

2- Tafseer Al-Fakhr al-Raazi, V.27. P. 165.

3- Tafseer Al-Qurtubim V.16, P.22 and 23.

4- Tafseer Ibn Arabi, V. 2, P. 219.

5- 'Tafseer Al-Tha'aalibi, الثعالبي V. 5, P. 157.

6- Yanabee' Al-Mawaddah by Al-Qondoozi Al-Hanafi, V. 2, P.332.

Wassalam.

We must submit to the Truth and believe in Allah being The Only God, all His messengers and the 12 divine successors after the Prophet Muhammad (SAWA) about whom the Prophet has mentioned and ordered every Muslim to keep following Quran and Ahlul Bayt (AS).

We need to follow and practice the orders of Allah and the Prophet and Ahlul Bayt and avoid sinful acts.

Wassalam.

It is recommended to pour water on the grave of a deceased immediately after burial as we read in many authentic Hadeeths. It helps the deceased in his grave.

Wassalam.