I'll second (third? fourth?) the whole idea of getting an instructor in the car with you ASAP. For what you (or ANY relative newbie) needs to learn, any decent tire will do perfectly well, and in fact, something in the 200-280 range would probably be perfect.
A couple of notes on tire behavior, and how R-compounds compare to their extreme-summer bretheren:
1) For what you need to learn (the line, braking technique, steering technique, picking consistent braking, turn-in, apex and track-out points, throttle techniques) the tires really don't matter. The bulk of this can be done on all-seasons, however they will hamper you to an extent once the concepts begin to "click."
2) Tires can be the most communicative part of the car! Listen to them. If you get a thin squeal intermittantly here and there, that lets you know that you're starting to approach the edge of the traction envelope; the tires are starting to wake up. If you get a nice, barking squeal the entire time from turn-in through track out, then you just nailed a perfect corner! You're right at the edge of the envelope. If you hear the tires howling, growling, or otherwise complaining, though, you know you just stepped past the sweet spot! R-compound tires, in comparison, are just silent, until you push them, then they're silent. At the very edge, they will make a tiny little growling noise, and then they go silent again as you spin off the track. Driving R-compound tires is more about feel than it is anything else, but until you can learn to control the car at the limit, they're more likely to hide bad habits than anything else, since there's no sense of impending doom as you start to push the envelope unknowingly.
3) The MOST important thing you can learn to do is to drive smoothly! Smooth on (and off) the brakes and throttle, smooth on the shifts (up AND down), and smooth on the wheel. When you're smooth, you will go faster than if you're throwing the car around. Period. If you're smooth, AND on the right line, you will go faster than you believe you can, and without effort. If you're choppy, though, you will NEVER be as fast is you think you should be...
4) With R-compounds, they either grip or they don't, and so they will hide over-aggressive driving. A good street tire, in comparison, will let you know you're mis-behaving, and if you step over the edge, are pretty easy to recover. Not so much with R-compounds. With street tires offering around 1.0G of grip, going a little past that will result in a bit of sliding around, and will feel unsettled. R-compounds, with around 1.4G of grip, just grab the pavement like velcro until you go too far. If you know how to manage weight transfer, slip angles, and throttle modulation, you can recover from one end breaking free, but if you don't, you're done. R-compounds have a narrow window where they LIKE to be driven, but without understanding what the chassis is communicating through the seat of your pants, it's far, far too easy to blow through that window, or worse, never hit it at all.
My advice: get an instructor in your car (NASA and HOD are both good for this!), and then learn how to drive it. Don't worry about modding the car, running race tires, or anything else, until you really understand what the car is telling you all the way around the track.
