When making rule changes it's important to understand why those rules exist and how changing them may affect your game, and if you're okay with that or not.

For instance, I removed level limits in my games, too. The reason for this, however, was because none of my games went past level 8, at most (at least, so far), so having level limits was pointless anyway. It didn't affect my game at all. (Also, my players tend to favor humans over demi-humans anyway, so I don't have to worry about running an all demi-human game).

You mentioned giving mages bonus spells, like clerics get. This would make mages more useful at low levels, but keep in mind that it will also make them even stronger at higher levels (and they are pretty dang strong at higher levels as it is). I usually prefer to give low level mages a temporary magic item to help them out in the earlier levels instead (a Wand of Magic Missiles, for instance) and have it dry out when they finally get strong enough to stand on their own.