Just a beginner, and not experience in car mechanics, so really don't give my view much credence, but having just gone through taking out the rear wheel and sticking in the Bleazy Bevel mount kit and replacing the wheel, I'd say for point 4) on the tensioners a turn or so would make a difference once up to tension.
This was based on just jacking up the rear wheel at spinning the wheel forwards to see where the the belt tracked. Adjusting the LH tensioner it was fairly easy to get the belt to sit such that it wasn't touching either side plate on the rear sprocket.
As for central alignment, I decide it didn't really matter if it crabbed a bit. With one wheel at the back and two at the front, I reckoned any possible non optimal wear patterns would be inconsequential compared to all the other things that will go wrong on it.
That said, given the variability in chassis dimensions that I noticed when fitting new shocks, I could imagine what works on one works less so on another!
