1. I've seen them at kmart.
4. Anywhere were they sell basketballs and footballs and soccerballs
Yep, I've ONLY seen them at KMarts. I've also seen nice ball pumps at Toy's R Us, even dual action jobbies.
I tried putting a dual action ball pump in a big blast, a cruder way than rork did, but I found that I couldn't seal it completely air-tight because it had holes in the front for the dual action part that would get covered if I gooped over it. So I would go with normal pumps. It doesn't really matter, because 1-2 pumps should fill the tank anyway.