The planes are pretty much identical to CO planes. Same cabin config and seats. Even the logo on the tail is similar. Meal service up front is similar to CO transcon service but only two choices. There is an ice cream sundae for dessert on lunch/dinner flights.

Yes, you can get upgraded on every Copa flight, including those to deep South America. It is a much different product than the CO 76s that go down that way, but the EUAs are there.

Upgrade chances are, well, chances. I've been rather successful historically but I've also done well on CO from PTY to/from IAH.