breaking the salaah

Ending one's Salaah before the imaam

Q: When I was in my prayer (I was waiting for the Imaam to end the prayer with salaam) in congregation,

1. I needed to use the washroom urgently. In that condition, is it permissible to end the prayer by myself and go to the washroom, or is it not permissible?

2. My stomach was well. If my stomach had been upset, would it be permissible to end salaah before the Imaam (the same act which is asked in Question 1)?

Intending to perform nafil salaah or to keep nafil fast

Q: In the one instance, one makes intention to keep a nafil fast or to perform a nafil salaat. But then, at the appropriate time, one changes one’s mind and does not keep the fast or perform the nafil salaat. In the second instance, one had already commenced performing nafil salaat but when one’s wudhu broke, one did not renew one’s wudhu and abandoned performing the nafil salaat. In the first instance, is it now mandatory to fast and perform the nafil salaat one had intended to perform? And, in the second instance, does performing the abandoned nafil salaat also become mandatory?

Being called while performing Salaah

Q: If a person is praying Zuhr salah at home and a family member calls him from another room, what is the best way to notify the family member that he is in Salaah? Is it ok for him to recite his qira'ah loudly for 1-2 seconds to show that he is praying (even if it is Zuhr salat), or should he say "subhaanallah" loudly or is there any better way?