Expansion of MD3600i (adding disk shelf)

I've currently got a couple of MD3600i's at sites; In the same sites I've a couple of Poweredge servers with MD1200 DAS SAS shelves.

I'm looking at removing the shelves from the Servers, and adding them to the 3600's. 

I'm not expecting any data on the shelves to transfer over, both 3600's have additional physical support feature keys. My only concern is that the MD3600's are 900GB drives, the MD1200's are 2TB drives.

My questions are:

1) Is what I'm planning feasible?

2) Would the new drives show up a separate available pool of storage? Again, I'm not going to be trying to spread any current Luns onto the new drives, just create new luns on these drives.

3) Is adding storage a hot swap event? Can I add the shelf via the external SAS or does it require power down?