Help fixing a hollow body guitar?

I found a 60's Maxitone Bruno hollow body guitar in my grandpa's closet. The guitar looks great after I replaced the strings, put the nut for the Input jack, and replaced the tip of the switch system. The guitar works when you plug it in but it gives a very loud and annoying humming sound when you plug it in, and when you distort it gets worst and sometimes make a sharp annoying sound. Also the two tone knobs are loose and while I'm here I wanted to ask if its ok to replace the floating bridge with a stratocaster bridge??