1) Some EZE flights have the new MAX9 with POD style lie-flat seats. These are easily identifiable with a MAX9 logo when choosing flights. Other flights might (should) have the 737-800 Version B, with better lounger seat and longer seat pitch, this is trickier to determine, only through evaluating the proposed seat map, and may change. CM coach still provides alcoholic beverages and a meal (2 on EZE flights I think).
3) The Copa lounge is long finished. Bigger, but still pretty uninspiring and certainly not worth planning for. An 8 hour layover permits a canal visit depending on avoiding rush hour.

Both topics are covered in several threads on this forum and in the Central America forum.