3:2 pulldown is a process of taking 24fps footage to 30fps by laying down the original 24fps frames in a repeating sequence of 3 fields and 2 fields. Given the film frames ABCD, you wind up with video frames AA AB BC CC DD where the first character represents field 1 and the second character is field 2.
WSSWW means "wiggle still still wiggle wiggle" which describes what the 3:2 frame sequence looks like after pulldown if you were to step through the frames. The various configurations you see of WSSWW in AE are so you can feed a piece of footage into AE of 24fps material (at 30fps) and undo the 3:2 sequence to get back the original whole 24 frames.. it needs to know how that sequence falls on your clip starting from the first frame in order to properly undo the pulldown.
Now, as far as how it helps you rendering, it doesn't -- arbitrarily anyway. If you had ***@30fps material that you removed the pulldown from, made a 24fps comp with it, but wanted to output a standard 30fps NTSC comp, you would render and put the pulldown back in. Or maybe you are doing cartoon-style animation in a comp at 12fps; To play back at the right speed in NTSC, you'd render at 30 with pulldown again to get back to 30fps.