The BOV is supposed to be resirc'd(if the car still has a 3Gmas and the intake with the resirc tube). When I had the car the rear power steering lines went out, so I cut the belt off. I spoke with the guy who sold it to you. He said he tried to patch the rears but then the front lines went? My plan was to try and find a steering rack out of a 1G and get rid of the rear lines. Now that the front lines are leaking I'd say searching for a non power steering rack and ditching the PS all together is your best bet.
The guy who sold it to you also told me he thought the decel rumble was from the the Throwout bearing. I don't know if I agree with that. When I owned the car I would get some chatter at idle with the clutch in. I thought that was the TO bearing. The decel rumble I've always thought was the Driveshaft not being shimmed correctly. There's a thread about that somewhere here. And a bad Lobro Joint on the DS.
As far as the wires and grounding goes, I don't think there's a particular way to set up the grounds. Check their website(Hotwires) to be certain, but I thought I just set them up so they looked clean and not all bunched up.