I had a topic maybe 20 days ago addressing some of these points, and if I was savvy I'd link it here, but:

You definitely cannot call Virgin for seats. CO's stock is CO's stock and Virgin's is Virgin's, and only at the airport will they release the seats to each other. I know this b/c Continental has 10AC and JK but Virgin has 10EF (the letters might be slightly off, but you get the idea - someone decided to put Virgin seats in between Continental ones, which strands a 3pax party, like mine).