"Does NCCS only allow you to make human companions?"
NCCS does not restrict you in any way -- you're still free to create whatever your modding skills and the GECK will allow while NCCS is active.
...No, that'll get me in trouble, no matter how funny it is...
Yes, in v0.7 the only included framework is the one for NPC-type (human and non-feral ghoul) companions.
Yeah, that's innocuous enough.
Wonder if anyone's observant enough to catch that I specified v0.7 only contains the one framework...