I can't speak to the rest, but I bought a pressure tester which I have used. The Allante cooling system is pretty sensitive and subject to leaks (aluminum block), so for me, it was a good investment. Cost around $100.
Essentially, its a small handpump with a fitting that attaches to the radiator cap hole and inflates a diaphram to seal the hole, then it pressurizes the system. I found that draining the fluid first is a big help, because it takes a lot of pressure to drive fluid out of a pinhole, but air will escape easily and make a noticeable noise.
When I did this, I found I had a couple of leaks at the hose clamps. On the particular car I was using it for, its possible to get leakage between the water jacket and cylinder liner. If you pull the plugs, you can supposedly (I didn't have this problem) hear the hissing into the cylinder. Dont' know if this is applicable to other engines - depends on the design I suppose.
As far as the cooling system, I pressurized it and found something else to do for a couple hours. When I came back, the gauge hadn't moved (after I tightened all the hose clamps) so I figured I was good to go.
Probably more than you wanted to know...