Summit Point is a great track! I was there 2 weeks ago with the NJBMWCCA. Some of the turns are a little rough, but it shouldn't bother you too much. If it's wet, be careful with the patched pavement - it gets slippery.
The front straight is fast. I get up to about 120 in my E46 328i, so an M3 should be quite a bit faster. Build speed slowly to check your braking zone - you don't want to run off the track at the end of the front straight. Turn one has some patch that you have to be careful of.
My favorite section is turn 3 to 5. You'll be accelerating up a hill in a gentle left hand sweep, then down the hill in a right hander. The track straightens out long enough to apply hard braking so you can make a hard left hand turn into the carosel. I also like the esses after the carosel. In fact, I like the whole track! The surrounding area is beautiful, as well.
You'll have a blast!