Just a few things, Gary. I don't think you have to be a regular
when you sign up for selection - the guys from CDO I knew who went
for selection were NSF when they did it. Also, once you're posted
to SOF, you stay there except when you're rotated through your
tours of duty, typically in 1 CDO (e.g. a CSM tour if you're a
specialist, or an OC tour if you're an officer).
As for the training, I was from 1 CDO, but some of my company mates
went over to force line, so I know a fair number of the guys there.
They don't talk much about the training, and I don't ask. What I do
know is that it's not so much a question of what you do, but what
the selection panel sees of how you do it.