Depends if they centralise the rack. Which you can't on a mk1/2/3 as you can't adjust the offside trackrod

When the o/s wheel is aligned, then the rack is centred. Therefore they only ever have to adjust the passenger side, to get it all perfectly set up. Most monkeys i've asked can't manage this simple task, so i do it myself.

If the steering wheel isn't straight with the o/s wheel aligned, it's been moved and needs to be put back on straight. It's never likely to be absolutely perfect though, due to tolerance variances between the nearest spline and all the suspension/steering components between there and the hub.

Should be correct yes. But with the likes of lowered cars it varies as the toe changes with the ride height change, however it should be pretty near, and they're a fixed ratio steering rack so it doesn't really matter :)

And yeah, there's movement on the bottom splines even with the flat for the pinch bolt