I would say 16 GB is the bare minimum. Oblivion for example needs about 10 GB, If you have discord, your Browser, and 1-2 other programs running in the background simultaneously, you will easily reach your limit.

Oblivion needs about stable 10GB with max settings on my System.

Yes. With every phone. Even with build in Gorilla glass, you will get scratches. I have never had any problems with sticking on the protective glass. No bubbles, no dust.

Thanks for this recommendation! You know some places where I find more of this?

You defentently need a case for the FP5. Without its very slippery.