Advanced shot? It's still there, only now there's a bar next to your character that will show exactly how much power you have after you set impact - you still have to judge power by the backswing. Putting with it is exactly the same as OOB.
It's unlockable in the store "Others" at some point along with 2 other shot types. It might not appear in the beginning though, and I don't remember what triggers it. The Others part of the store will expand massively as you play through Challenge mode though - I know that much.
I hear you on the Lv. 4 and 5 DLC as it unbalances multiplayer. Fortunately you really only need to buy two Lv. 5's to keep up - the Big Magnum club and Big Air ball. You don't even have to buy the Lv. 4's first to get them.