Fittings for coolant

[JimT]

Looking to add a couple shutoff valves to the back of the engine to control coolant flow to unnecessary accessories, like the bunk heat in the summer. Also need to replace a damaged manifold pipe (that peterbilt wants to charge a couple hundred bucks for) with easily accessible off the shelf parts (hoses, T's, etc...). Are there any particular types of valves or fittings or pipe (copper, brass, etc...) which I should either stay away from or prefer over others? Anything I have to watch out for with the newer coolant? Might be a silly question, but I'd rather ask than assume.