I'm just hoping for some info on how this works with CO.

We purchased a 4 segment coach ticket (U class) and did a 15,000 mile $75 each way upgrade. The first outbound and first return segments allowed us to choose our seats and looks confirmed (R class) but we were waitlisted for the other two segments.

My question:
1) Since we got to choose our seats are we really confirmed?
2) The waitlisted flights actually had more seats available than the other segments. Is there any rhyme or reason to how this works?

Thank you, I'm looking forward to my first time on CO metal in a LONG time.