Lots of doubts with GUPs

 The documentation on GUPs, doesn't use any illustration examples, hence I guess I am having a super hard time with it.

Not to mention things with GUPs never seem to be working as they should, I appoint a GUP for a machine then check the debug log on the machine and there's no mention of the GUP IP in there anywhere.

I have some questions below, appreciate if one can answer.

1. When the gup and the client are in different groups but same subnet? (using single GUP)
2. When the gup and client are in the same group but different subnet? (And the routing is avaliable and ports are open.)
3. If multiple gups are created in the same group then will the clients use them on the avalaibility basis or will they all just use 1 gup? Can there be any load balancing here?
4. What if I appoint the same machine as the GUP for 2 different groups using "single GUP" in both the group policies?