Since the really smart people aren't chiming in, I'll offer up my two cents. I'd suggest an exhaustive search of the wheel and tire forum as well as the suspension forum. Somebody has probably done what you want to do, or didn't do it because of a problem. Either way, you will probably find enough information to get some of the basic issues worked out.
For what it's worth, 17 inch wheels will probably fit the TS (the tire rack has 205/45/17 listed as an option. I can't imagine the springs dropping the car enough to cause any problems, but you never know!
Cheers and enjoy your TS.