Generally speaking, I agree... save I do think any creature/thing with any source of magic resistance is generally capable of 'accepting' a friendly affect if it desires to unless the MR source is flawed to prevent this. Is consensus that all MR is inherently 'stockade' as it were?
I suppose that depends on his powers of travel. However, whatever spell/effect you employ to control him becomes disrupted once he crosses anywhere. Within a Boundary everything functions normal. But to send him to another location in the Realm or to the Terrestrial sphere ends your conrol spell.