I am doing part of what you are wanting to do. I would like to do all of it, but I have not figured the rest of it out.
I have both of my Google Voice numbers set op on my 3 1032s. When a call comes in, all 3 1032s ring. However, if you are on a call on one of the 1032s, you cannot tell if that line is busy on the other 2 1032s.
I would also like to be able to put a call on hold on one 1032 and pick it up on another but I cannot do that at this time either.
I am hoping that they make the 1032s work with OBiPlus and let a 1032 be a master. This would let everything work the way I want it to.