Repentance and tawbah

Q: From my childhood I was disobedient to Allah Ta'ala. I have committed so many major sins. I feel no regrets for the sins I have committed. I have spent all my life in committing sins and I never cared about Allah Ta'ala. But now I want to change for the better. Will Allah accept me? Can I become a good slave keeping in mind my dark past?

Rennet

Q: Recently, I found out that it is likely that most cheeses in fritolay snacks contain rennet from animals slaughtered in a haram manner. Does that make the cheese haram too? I'm confused about this because I used to get those snacks in the masjid when I was younger.

Fear of performing salaah with jamaat in a musjid

Q: I have researched about it deeply and I can conclude that there are cases in which it is recommended by our religion to pray alone instead of attending congregational prayers such as when you feel that your life or assets are in danger, in state of fear of your death, etc. Hence my situation is that I love to pray in the masjid with all the people together but whenever I enter the masjid, I suspect everyone as a suicide bomber. During whole prayer I am not able to concentrate in my Salah, this happened more intense when I bring my kids with me at Juma or even daily prayers. During prayer I start to imagine blood and body parts on the carpet and during whole prayers my mind is busy in thinking that if it really happens, how I will save my kids? From where will we escape, etc. I feel much better praying alone in my house or more better in an empty masjid. My question is that in that case what should be the right thing to do?