I would go with an SPC camber kit before a S2 one. The A-arms have been known to rub on the inner fenderwell, and the hardware craps out if you drive hard. Most people with the skunk2 kit have to upgrade all the bolts and whatnot just to get it not to slip during HPDEs. But they also hold up just fine for some. I've never heard of anyone having a problem with the SPC balljoints though.

As for allignment, I personally find -2.5 front, -1.5 rear camber to be a good combination for autocross... zero toe all around. If you autocross a lot, the tires will actually wear pretty evenly with this setting... Do too much highway driving, and you'll have some camber wear though.