According to the Miami Heat, you only need three. Actually, they're going to trade the three they have under contract for Chris Bosh. I guess Miami thinks you need only one.
Pretty over-rated IMO. If you have a solid front office, great coaching staff, and a very loyal passionate fanbase, you could still probably finish ahead of New Jersey without having any actual players. However, I would strongly recommend teams to have a few.
What if Paul Allen dumped every player and made me GM! I signed 14 of you guys...... I would be the starting PF of course. I bet 5,000 will still show up per home game to watch the magic on the court! Who would coach? Mrs. BeerBoy would be the halftime "entertainment" thats for sure.
Well that all depends. For instance, last year if you were in New Jersey, 15 people off the street with a high school coach would have only won 12 less games than the Nets!