A: No, it cannot regulate pressure. It is a hydronic check valve only.
A: No - it is strictly a check valve. If you are trying to reduce the incoming water pressure from the street, there are pressure reducing valves available. I reduced mine from 80 down to about 65 psi.
A: On my 4-zone system, the hot water comes out of the boiler and goes into a cast iron manifold. I have a flow check valve attached to each outlets of the manifold. It goes through the check valve, across the basement, then up to the first register of that heating loop. It goes through the rest of the registers, then back down into the basement, being PULLED by the circulator pump (I have 1 circ pump per zone). It goes through the circulator pump, back into the boiler, then out again to the manifold for another pass through the circuit.
A: The installation sheet, complete with diagrams, may be viewed here: http://media.wattswater.com/1910220.pdf