I've never used the full version of CCE, only CCE Basic. You don't need a front end program...you can import avi files and convert to mpeg2 using just the encoder. It is a professional level program though, and won't hold your hand through the process. You're expected to know how to get the settings adjusted correctly.

Getting the mpeg2 to dvd format is a separate step, though you could use AVI2DVD in this whole process. I've just gotten used to using a different program for authoring.

CCE SP is able to utilize multiple cpus as far as I know. But only going from what I've read, since I haven't used the full program. And since I switched to ProCoder, I don't even use the Basic version. ProCoder is an entirely different encoding program by the way, no relationship to CCE at all.