Yes, they do. If you go to the hunting section of the store (with all the airsoft, paintball, Archery, guns, and ammo) and ask the sales associate, behind the desk with the guns, he should be more than willing to help you.
Yes, in the back where all hunting and guns are
Yes they do.
No, but Dicks sporting goods does.
Any sporting goods store that sells paintball supplies (Dick's Sporting Goods)
Take it to a shop! if you want to do it yourself the normal way is to put the bottle on scales and fill it from a larger bottle to a fill weight. To be honest though CO2 is well out of date. A smart move would be to move onto compressed air.
At some sporting goods stores, all paintball fields, and any places that sell bulk gas like propane, and oxygen.
CO2 tanks are easy. now that paintball is getting really popular you are seeing more places that fill tanks. any paintball shop (of course) will fill it and even places like Dick's. Just try anywhere that sells paintball gear.
At a paintball or sporting goods store.
Many of the retail sporting goods stores will have refill stations for your cylinders. Also, I have seen hardware stores that will do that too. Where did you buy the gun? Chances are that the store the gun was purchased from will be able to refill the cylinder for you.
You can purchase them at most sporting good stores like Dicks, Walmart, Big 5, Cabelas or Bass Pro.
Dick's Sporting Goods
dicks
To the best of my knowledge, WM does not sell CO2. Acadamy does in the Dallas area and so do most paintball stores. But just for a heads up, a lot of stores are going away from CO2. It has become a commodity that is more exspensive than for N2 or compressed air. The stores are charging less for HPA than for CO2. You can get a 48ci 3000 psi tank for less than $90 in most cases.
If it has threads on the top, you refill it like any other tank by taking it to a sporting goods store or paintball field. If it does not, then it is a disposable, and you cannot refill it.