I believe a few of the 733s (oldest aircrafts in CO's fleet) do have dropped down screens. Not all though.

To get exit row or bulkhead seats, you can try it at online check-in. Do it ASAP, starting 24 hours before your first leg. All available are opened to everybody then. You can check-in as many times as you like and you can try change seats again at a kiosk at the airport.