I think a strict prescriptivist would tell you that you need a comma before "and" in the ones that have two independent clauses. However, I think the extra comma will come across as fussy and inhibit rather than aid readability. My rule of "most readable" trumps "comma between two independent clauses joined by a FANBOYS conjunction" in my book, so I'd omit it.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.