why can't NPCs have a familiar ? what's the thinking there ?
also, would I run across any problems importing a PC with a familiar into a multi-player game to turn them into an NPC with a familiar ? (and then swapping it back to single-player of course)

So you want a party of 12?
Man, that won't be called a party, it will be called an army!
That is my reason... as for you other question.. I have no comments...

I dunno. I always thought that the familiars were poorly implemented.

With the exception of the ferret in a solo game they are all pretty useless as the general power level makes combat too dangerous for them. The dialogue with them quickly gets old. I wish they were given a bit more dialogue. Perhaps some cute lines of their own if you made them talk to NPC's and stuff. A rivalry with Boo could be fun too.

Perhaps it would make a problem having more then one familiar in a party, there could be some variables and who-knows-what.
I think every class (both protagonist and NPCs) should have familiars. Why couldn't ranger have a rabbit (or wolf or bear for instance), or paladin have a pseudodragon?

On that note - there's nothing stopping other classes from having familiars. From what I can tell, anyone who can either cast Mage spells, or use their scrolls can have one. In a previous solo game my thief had a cat familiar and as soon as I get 3m XP my current Assassin will have one.

Could a bard cast find familiar?

A bard can cast Find Familiar, why shouldn't he? It is a first level mage spell.

well if they can cast find familiars....dont u think u will be a bit over powered?.....i mean the familiar gives half of there HP to urs
and since ranger and paladin already have high HP.....well u get it.....i think the familiar should just be left for magic users....that includes NPCs