Is it permissible to repeat the Istikhara (seeking guidance) prayer, and is it a condition that one should sleep after offering it?
All perfect praise be to Allah,The Lord of The Worlds Istikhara is offered once, but it is permissible to repeat it, and sleeping after offering it is not a condition for its validity. And Allah Knows Best.
What is the ruling on loudly sending prayers on the Prophet (PBUH ) after the call for prayer Athaan?
All perfect praise be to Allah, The Lord of The Worlds Sending prayers on the Prophet after Athaan is a Sunnah for the Mou`zen (caller for prayer ) and the hearer. However, there is no harm in doing it loudly after the end of Athaan, but sometimes, it shouldn`t so that people wouldn`t think that it is an integral part of the Athaan. And Allah Knows Best.
What is the expiation for breaking fast due to being on a journey, or being sick, or being in a state of menstruation?
No expiation is due on the aforesaid categories, but they are obliged to make up for the missed fast. However, if any of them failed to do so while being able to, and the next Ramadhaan has come, then making up for those days is incumbent on him/her , and paying the ransom as well. And Allah Knows Best.
What is the torment of the grave?
We seek refuge in Allah from the torment of the grave. The important point is that the cause of the torment of the grave is disbelief or committing sins without repentance. It affects the soul, and the body is impacted by it, even if we do not see it. And Allah Knows Best.