I can’t answer the second or third questions, however, for the first, side closures are good for completely sleeveless vests, or, at most, ones with shoulder wings to attach the pauldrons, not vests with sleeves. If you want sleeves on your vest, go with either a back closure or a front closure. I personally prefer front closing vests because they’re easier to put on and take off by yourself, as you won’t need someone else to zip you up in back.