1. Not sure. I've never tried to input a drive this high so someone else may be better at commenting on this. Are you referring to one drive that is 3TB in size or are you talking about a drive pool where the pool is 3TB in size? If you are talking about the drive pool, it should be fine. Can someone comment on this?
2. If you go to the forum posting for the Gen3 debug cable (linked
here), at the top of that posting it will say whether the service to build a cable is still available. As of this date (11/27/2012), the service is open so you should be set to go. If the top of the posting says the service is closed, then you will have to resort to other means to access the internal functionality of your server.
Hope this helps.
Charles
ps: Welcome to the forums.