With the precision gates, the spring shouldn't matter a whole not if you plumb it correctly. And as for tuning the gate, it is one of those things where it will make more sense once you have it installed and in front of you.
Crank the gate clockwise all the way to shut the regulator completely (Basically it's like not have a gate in the system). Then make small counter clockwise adjustments (1/4 turn or so opening the gate back up) until back pressure/boost is where you want it, or where it's safe. There should be a magic spot where it makes the best power and retains good driving characteristics. I would get it close on the street, and then fine tune it on a dyno if you have access to one.