Fast food shop adding an extra item into one's meal

Q: I was at this fastfood shop last week and I bought a 3 chicken wings meal. I came home and saw that I was given 4. Normally I don’t worry about this since usually I assume this occurs if one of the wing pieces is small so they give another to compensate, however, because I’m dealing with religious OCD and doubts, I’m worried. I called them today and they confirmed that sometimes they do this for the reason I mentioned above. Can I assume that this is what occurred in my case instead of thinking that they made a mistake?

Developing an app

Q: I am a software developer and two weeks ago my friend asked that he has signed a deal with his client for an android app that we need to deliver within 30 days. My friend and his client both are very trusted although the client is a non-Muslim. So what happened is neither he saw the project details nor me and after two week now when I started working on the project I realized that it was a betting app. Me and my friend both are very stressed that should we take the money from this app or not? Since he has transfered the money into our bank account, what should we do?

New Muslim feeling like a failure

Q: I am a new revert and my family doesn't know. They would completely disown me or hurt me if they knew. I sometimes struggle with doing prayer because they are there and lately I am also taking care of my sick father and cannot always do wudu or find the qibla at the hospital for prayer. What do I do? I feel like I'm failing.

Calculating zakaat according to the nisaab of gold and silver

Q: If in 2017 and 2018 a person followed the silver nisab but happened to not pay Zakah in those years despite meeting the silver Nisaab then at a later point (maybe 2018 onwards) he moved to the gold nisaab and when he did calculation for past Zakah, he used the gold nisaab retroactively, even for those years where he followed silver nisaab but that meant for those years he did not owe Zakah according to gold nisaab. Would he be required to still pay Zakah for those two years because at the time of those two years he was following silver nisaab?