Is there a limit for the maximum cc the game can handle?

Sounds like you could have some bad CC.I've downloaded a few from that site and had to remove them as every
time I used it, it would crash my game.

Merging your package files together is very easy and I do all the time now =) Best tip would be to create a folder on your desktop and name
it something random, then put all the .package files you want to merge in there, then merge them.

Its recommended that you don't merge patterns, and I wouldn't merge gameplay mods like Nraas and some of those..but that's just me.