Welcome to the party!
My advice would be to sort out all your suspension and get tires, after that worry about power and weight reduction. Alignment is very important on these cars. Since I didn't have rear camber arms I used ride height to set rear camber and adjusted the front height accordingly. Good luck, there are plenty of people here willing to help. Also, do some reading around on tires. The RS3's and Z2's are also good tires depending on surface and temperatures.