Right. That's the only way that the EQEmu project avoids litigation is by not distributing any actual Sony files. The less said about them around here, the better.
As for the rest, there are some classes that don't do as well on EQEmu. I've personally found Enchanters to be fairly weak, since their charms don't always work as they would on Live. Also, some classes have more broken AAs than others. I know that mages do pretty well, but they have a significant amount of AAs for their pets that aren't functional currently. I play a SK, and actually find them to be pretty well off. There's a few hiccups here and there, but at least Improved Harm Touch doesn't target me automatically when I cast it anymore
Tradeskills are a different issue, as those depend upon which database you use. If you join a server that's using the PEQ (ProjectEQ) database, the majority of tradeskills that they have working are up through Planes of Power and Ykesha with a few exceptions. Quests are the same deal, as some servers have their own databases and some will use PEQ's quests. Any quests that work have been written by someone, which is what makes this project interesting to me. Not only can you play and have fun, but you can enjoy quest writing and contributing to the project, even with minimal talent (like mine!).