Various Gun Problems

Hello, I’ve been following a (slightly outdated) FPS tutorial series FPS from scratch - YouTube
I have 2 major problems that I can’t get past and the creator hasn’t responded to me after 3 emails and a lot of time. I was wondering if anyone here knew how to solve them.
My first problem is that when switching weapons, only the second weapon I grab is usable, and the other stays on my back. My other problem is both weapons fire at the same time and even when they’re not in my inventory.
I have the creator’s reference project if you need it, but I just really want these issues fixed.