Tile on Plywood rules?

Hi everyone,

I recently remove vinyl tile flooring in my house for two reasons.

First, didn't like it and wanted to place some tile in kitchen and bathroom.

Second, the floor was very squeaky in spots.

My questions are the plywood subfloor in spots is a little beat up in some spots there is adhesive sticking to the subfloor.

What is the best course of action at this point to patch up or fix the floor so that I can get it read to lay my new tile? Does it make sense to remove a piece of subfloor and put a new one if the floor is really bad?

Also, to eliminate the squeaking should I just go through it and screw the subfloor into my joists every X inches?

Thanks

Tile on Plywood rules?