No worries, it may be worth getting a couple of the yellow pads, as I'd imagine you'd use these the most...
Let me know when you get it, and I'll link you up with some threads and vids to teach you how to use it. Just get used to 'steering' the rotary first, before contemplating any heavy correction, else you're asking for trouble, so 205 on a blue pad, and just learn how to use it, then step up as and when you feel ready.
A paint depth gauge is worth looking at too, but they aren't cheap. Remember, heat is your enemy too, especially on plastic...