I guess it depends...
Are you serving a side? If yes, how many? Are you making sandwiches? How old is the crowd? (I go with more if it's younger vs less if its a group of 70 year olds vs a bunch of kids (under 12)).
As for keeping it moist, take a look at how others deal with it in Brians thread
pulled pork sauced?
BTW, do us a favor and swing by '
Cattle Call !!!" and introduce your self...