CerebralAssassin
First Post
When the group I play with went through SC, we had a thief, but no arcane caster. I'm not sure if the module would have been doable without a thief, but then again our thief found several of the traps the hard way 
I think if you wish to add an NPC, don't plan on Meepo living. While we didn't kill him (monsters took care of that for us), we also weren't especially concerned about his survival.
I also think that the core books will prove sufficient in terms of offering enough options for your PCs.
Nathan

I think if you wish to add an NPC, don't plan on Meepo living. While we didn't kill him (monsters took care of that for us), we also weren't especially concerned about his survival.
I also think that the core books will prove sufficient in terms of offering enough options for your PCs.
Nathan