Arena draft, you can get more than the usual limit of 2 on a card.

Nope, the front of the body is considered the position of honor on a person, so the stars are placed on that side. You'll see this with the patches that the military wears.

Or you can play well and get at least 7 wins in arena, at which point you are guaranteed to get enough gold for another arena run, plus the pack reward. And doing the arena runs can complete your quests as well. Simply put, being good at arena can fund your entire ranked deck if that's how you choose to play.

Lol nope, you can't actually buy individual cards, and you can get any card in the game by grinding arena and quests. It's entirely possible to get to legend without any legendaries and many prominent streamers have already done so.