Non-combat pets are just that, non-combat pets. They scurry, flutter, or hover around you. Do nothing but look cute. They don't take commands. /shrugs
Check JAEFo's posts for current locations to buy them, he's even got the prices. The only thing he didn't mention was faction. Currently there is no method available for Alliance to faction up to buy from Horde vendors (or verse a vice), so your limited to what vendors you can deal with.
Same with Mounts. Most pet vendors are near a mount vendor, also. Mounts require lvl 40+, 100g to buy and 100sp to learn to ride.
Might want a pet guide for Warlock pets (combat pets), imp, voidwalker and succubus. They can be passive, defensive, agressive and I thought there was a fourth setting. They sit (guard) and attack. Attack can be your target, or a mob nearby (if on agressive mode) or whatever hit you last.
Lenari: Nightelf, Priest; Beta Server