shark bite

I do all the plumbing for our projects. He does all the electrical. There is a space I just cannot get to due to physical limitations: the crawl space. We have needed a few small plumbing alterations there and we really cannot use a torch, trust me, I would if I could. (Insulation limited...

Is there a preferred method of connecting pipes and fittings? I am familiar with ProPress, Sweat, NPT threaded, and sharkbite and FasTec. Is there any good reason to choose one over the other? or any reason to stay away from any of them? What is most popular among plumbers here in the US?

I want to use a 1 inch sharkbite elbow to receive a 1 inch copper pipe coming down from a hot water cast iron radiator. I want to do this because the floor linoleum is crappy and will need to be replaced. I want to make it easier to move the radiator out of the way. I got a better tube cutter...

I'm the facilities manager at a not-for-profit youth center. I need to deal with three 1 1/2" dielectric unions (code requirement) on two 100 gal. water heaters. At least they appear to be 1 1/2". In each case a ring of corrosion has formed around the steel side of the union/galvanized nipple...