I take it you have massive rich parents or a massive sponsor lined up mate.
As for joining the 2009 ACU 125 cup, you are too late. Cute off point was in Novemeber.
As it happens the RS would be no good in this class anyway. Too slow and heavy.
Do a google search on the J&S 125 Aprillia cup. Cant be bothered to find the website, but if you want it, you'll find it for your self.
Good luck.