If you go with a clutch Look at South Bend Clutch, very solid quality and outstanding price.
I just replaced my clutch in my 04 WRX wagon and it was... interesting.
Don't look to the guides on NASIOC, I found around four of them together were very helpful, but alone just confused me or skipped steps.
You don't have to pull the motor, it helps ALOT when freeing the transmission from the motor itself but its a lot of work to get it out. Plus its a tight squeeze with it in there.
The hardest part of the install was getting the transmission to break free, after 75K of wyoming winters and road debris it was a challenge but nothing a giant pry bar at a slow steady pace couldn't fix
If you have the money, have someone do it for you. If you can't imagine your baby in the hands of someone else (my case) its not that bad, a 4 out of 5 in difficulty though.