1)I really like the idea of the upkeep, but instead of balancing it by lowering/uppin it I think it would be wise to think about the previous xp/gold xp system to balance the whole thing.
I think both system are pretty viable and needed together, multiplicater / time based + xps/gold per kill, It may even solves future problems of a sole time based system.
2)While Im not really an active archer, I noticed the accuracy was kinda bad even with a good WPF and think it may deserves more balancing.
3) Horse Upkeep - I guess its a bug, need some emergency fix ;)
4) Repairing shouldnt be random, the random factor in a game that requires a lot of timing and practice should be reduced everywhere it can be, it's my opinion. It could be worked so it adds a deeper economic factor to the game, but you, as a player, got to have a better control over it than now.
Sorry for my low english skills and thanks for reading.