What are the PROs and CONs of using the OPTION STRICT command and should I go through my game and remake it to use OPTION STRICT?

No cons other than having to type more. You dont have to but it can help prevent using the wrong variable.

Cons: Initializing a variable inside a branch statement (IF...THEN) gives strange behavior to future variable initialization, more typing/planning Pros: Allows cleaner code, catch bugs immediately upon pressing start, you organize your variables better, it replicates a serious programming language, it gets you into a good habit, in the long run it allows you to make huge projects much easier.