Just an FYI on this. If these kegs have the name of a brewery on them they are the property of that brewery and would be considered stolen property if they are used by you. If they are not the property of the brewery be VERY CAREFUL not to hurt yourself when taking them apart. They do not have pressure relief valves and people have been hurt in the past taking them apart and finding out they have pressure in them when the ball shoots out into your head. As far as filling them and cleaning them it is not near as easy as a soda tank that many people use, but one way I hear about people doing this is leaving the valve on and using a sanke tap with the check valve (usually a little ball inside the top of the tap) to bring in cleaning solution and later beer. In my opinion (and I sell both types of kegs) the ball lock or pin lock homebrew kegs are much easier to use for a homebrewer and you don't have to worry about the "ownership" issues in possibly using a breweries keg. Breweries typically pay over $100 to replace a keg that does not come back to them.