Same as above, never heard of beta-alanine. That would help with training performance, but can't see it doing anything for getting on stage.
Creatine, yes, it will help fill out your muscles and draw in water to help with fullness. I used creapure creatine and was fine. Don't just give it a go on show day, do a trial run with it beforehand (like a week or two) to get your dosing right. You don't want to take too much so it causes stomach cramps or anything