I am not that good at many of the underlying rules either. But I do know what is and isn't grammatical.

Here are the simple rules to using commas before "and": The only time you don't do it is when you're making a list with two items. "My friends are called Joe and Jill." If it splits a sentence into two distinct parts, you always need a comma. If you're making a list with more than two items, that's a point of contention. I support using the Oxford comma, so I say you should.