Sorry to be getting back with you so late. I've been in the studio all
night.
Absolutely.
Just select whatever tracks you want to work with, then hit Command+A.
Another way, though more tedious, would be to select the tracks you want
to work with in your track list table, then press return to go to the
beginning of your session, then option+shift+return to select to the end
of the session.
I really haven't done much with splitting clips/regions. So, there's a
possibility that if you have multiple regions in a session, this might
not work using the second method I outlined. I'm not entirely sure. The
first method definitely! will work though.
Chris.