Hi, some quick answers are; 1. Currently units do not change appearance as they upgrade, (i'd expect this to change in the future). 2. For orc players who have wargs spawn they do get stronger as they mature, otherwise players buy the same strength warg units from the mercenary merchants in orc towns. 3. Buildings and walls can't be upgraded visually but each region has a different looking stone wall and each race shares a palisade wall look.
When I'm not in my right mind my left gets kind of crowded.