Wow! Feist is one of my favorite authors, so I love the idea! Sorry I have absolutely no modding experience, but at least you know there are other fans out here that would love a Midkemia mod!
I noticed you were wondering what else you could add for bandits... You could have just generic bandit groups as those were quite prevalent in the books. In the empire of Kesh there were always bands of desert raiders and slavers around. Also, you could consider having roaming groups of Nighthawks perhaps. Or maybe just have them randomly ambush the player in cities, like the normal bandits do in the native version.
Just some ideas.