I've never played a Might and Magic game before and I'm actually having a lot fun with this game so far (exploring the first temple). My question is what is the max character level and what is the max level for skills? Also, at what skill level can I upgrade to expert, master, etc? Thank you.

Ive never reached the max lvl so cant help there....but its probably way over 100.

Expert skills need rank 4
Master skills need rank 7 (some need a specific stat too like 50 end for master body building)
GM Skills need rank 10

You can just keep increasing skills over and above GM if you want, but for some skills its pointless, like repair, merchant, disarm etc...

Also, as you advance in skills, it becomes more expensive to do so, so be careful with how you allocate skill points. You should be sure you need the skill, otherwise it's pointless.