Miscellaneous masaail of Janaazah

Q: Is everyone buried in Jannatul Baqee an automatic Jannati? 

Were the hypocrites from the time of Nabi (sallallahu alayhi wasallam) also buried in Jannatul Baqi?

Q: Can a husband prevent his wife from going to her mother's funeral? 

His excuse is that because the janazah is delayed, they cannot attend the funeral according to shar'iah and his wife cannot go as it is incorrect. According to him (& nobody else), the mayyit made a wasiyat to be buried immediately.

Q: Will the people of the grave know what will be happening on the earth?

Q: My child passed away at the age of 17 months due to a brain tumor. He could literally speak 2 to 3 words and started to walk. Will my baby be entitled for Jannah? 

Q: Is it true that if a person passes away in salaah they go straight to jannah and if so, is there any hadith provided?

Q: Is there a dua or zikr or action a person can do to pass away with imaan?

Q: Is it necessary to deactivate the social media account of a deceased person? The person only has a few photos on their account.

Q: Is it jaaiz to seal the grave with concrete so that no one else could be buried there?

Q: I am scared of death and please tell me what happens after death. I was so scared at night.

Q: Is it permissible for a Muslim doctor to carry out post-mortems on bodies?