1) I would go ahead and pick up the HPI alu. threaded shocks. Find out the recommended spring rates from racers at your track.
2) Popsracer is right. A 2 speed will give you better accel. and topend, and your motor will run cooler.
3) Tires, tires, tires. Find out the preferred tire/insert setup at your track.
4) You don't need to get a new motor just yet, if you pick up a 2-needle carb, a bigger cooling head, and the smooth mandrel bent aluminum header from the Type SS, that's plenty of power to learn to race with.