Unless you are going to be creating lots of motion graphics in Motion, you don’t need 12 GB of RAM. If I remember correctly, FCP doesn’t use more than 4GB of RAM, might only be 2GB.
Also, I don’t think you can upgrade the CPU in a Mac without buying a new Mac.
Apple’s basic video cards are fine. What you do need is an AJA Kona or Blackmagic card to use for external monitoring.
4GB of RAM should be fine. Like I said before, if you are going to do a lot of work in Motion (or After Effects), then definitely load up on RAM. But if all you’re doing is cutting video in FCP, 4GB is fine. And, RAM doesn’t help with rendering. If you want faster renders, you need a fast CPU
As for a RAID…do you need a RAID? You haven’t mentioned what kind of video you are cutting. If you do, Sonnet makes good RAID cards.
