1:The water feed on the RB comes out of the block under cylinder 5. The T above the turbos is the return and actually returns it to 2 locations, the top radiator hose and also back around into the underside of the plenum. I believe its got something to do with balancing for the thermostat not being open perhaps? Either way you could just feed it straight back into there, but a lot of people just feed it back only to the radiator hose around the front of the cam covers and delete the entire rear line with no issues.
2: If possible, yes. Feed should be lower, return higher, and side to side. However if you can't do any of these things then try do as much as you can. Shouldn't be to much of an issue with a RB in a R chassis though.