1: The Xodus 2 kinda blows. You can get started with it but I really recommend a Go Big, Fiesta XX or even a Shinwoo Griffin Wing if you want to go cheap. The Xodus 2 breaks rather easily.
2: Depending on how you take to it, 4A isn’t terribly difficult to get into. I was throwing and catching almost immediately. Some of your 1A stuff will apply. Mastery, well, who knows. I find all this yoyo stuff difficult. I can do some 4A.
3: Off-string is 4A. Is that what you mean?
4: Learn the basic throw/catch/bind. Then barrel rolls, sun, pops and you’ll start feeling good. After that, L/R pops are good to learn. Whips and open whip binds are fun too. Learn Inifnite Star, you’ll really think you’re onto something and it looks darn cool too.