Only time original ren gave upgrades was certain servers that gave you an ingame "rank up" when you got a certain number of points - was a server side mod and upgrades only lasted until the game ended. Either way, complicated and unnecessary I would suggest.
Simple server rankings would be the most important I think, it means players have a reason to keep playing and to keep returning to the same server, which in turn helps to build a community. Just a running total of points/kills/deaths/games played and maybe buildings/vehicles destroyed, to be reset every month - ideally that can be checked in game and/or announced when you join.
Medals were awarded for MVP (most points), Best K/D & Most kills and via the !rec command and they never really did anything apart from being a lasting record of how much you had played on a server. Great if they are easy to add but don't really think a complicated medal system would bring much to the game.