To get better with tuning, you can look up how to tune a car for drifting online. And you will get better with a lot of trial/error. Best thing to do, is to do some research on the web. Goodluck
Definitely going to have to fix the 2-3 shift, aside from that, it has more than adequate performance stock to get a drift car out of it with the right tune. I have to agree with what was just said, see how others approached their drift tunes and see how it can improve your own tune. MR car have tremendous turn-in capabilities and the S7 could well end up being something special.