I had read an article somewhere, where a person used a two holed cork and some tubeing to connect the mini kegs to a CO2 dispenseing system. I cannot find the article but it looked easy.
As for re-using the cans, you can use them multiple times, however, the cans are "coated" on the inside to prevent the acidic beer from pulling the passivated aluminum layer off the walls of the keg. After a few uses, (and bumping) the coating gets cracked and allows the aluminum to add flavors to yoru beer. So if you are careful, they can be re-used a lot!