Ari,
After reading this exceedingly long string, here is my opinion on what may be the best course of action for you, in your motoring endeavors.
Ask Dad to lease the 330ci for you on a 3 yr term, this way you can have all the car that you can handle, drop the top, drive a few of your friends around, and pick up girls who will be happy to drop their top for you. Get an auto, there is going to be a whole lot of other things that you should be focusing on, rather then shifting. Besides, this also gives you a free hand, remember the comment about girls. Believe me they practically fall all over themselves when the see a Cab Bimmer.
I don't really know your geography, but from reading the string it looks to me that your town is a suburb, which means that you have access to allot of very good roads. This is the places where you really need to be on your toes. City driving is relatively easy when you are paying attention, and traffic is usually moving @ a slower rate. When on an open road, its just that, wide open, and the car which you're going to be piloting will be begging for you to give it hell. I can't stress to you how important it is for you to control your car, it's a beast, and it will be begging you for more every time you touch the gas.
Once the lease is up, and assuming that you have not caused major damage to both you and the car, then you can should look into getting an M. You will have several benefits to waiting this time out. First off, you will have 3 years of, hopefully, safe driving. Secondly, your insurance will be more reasonable. “Reasonable insurance” haha, for a 19 year old driving an M3, that's a phrase that i never thought i would use. Lastly, during those 3 seemingly long years of driving your “lowly” or “beginners” 330ci you will have that entire time to dream of the M that you will have one day. Getting an M right off the bat is like losing your virginity to a Porn star, everything else is never even close!!!! Come to think about it, if you were to get the M, and live to need a new car, the natural progression would be for you improve on what you already have. What's next? An M5, or why not just get an F360 Modena.
I'm sure that all of the gents which have read this string and contributed to it, all remember very well those long ago days of being 16, when we knew everything, and the world was ours for the taking, that is why we have tried to tell you that the M is WAY too much car for you, right now. Take it from the consensus, don't rush into a Supercar.
One last point. Putting a SC on an M3 is pretty much a waste of time / money unless you are serious about taking the car lapping. If you want to mod your car, do it slowly, upgrade the exhaust, chip, intake, plugs, wires, coil, etc....... don't dive into forced induction until you have done everything else to your engine, and you are still looking for more fun. By taking the slow and steady route, you will know your car, and yourself a whole lot better. Also, by doing all of these little things, either yourself or having a Mechanic do it, will only add to your knowledge of tuning a car.
Good Luck!
Papa G