Hi, I know I'm over half a year late replying to this, not checking this account very often. Glad you could revisit an old game like this, there are definitely other mobile games I wish had been preserved in a easy to play manner. And I had never considered the weapon switch thing, kind of like Doom Eternal weapon swapping to override firing animations, love it.
To answer your question on full screen, yes, just hit Alt+Enter at any time to toggle between full screen and windowed.