Thought I saw a post earlier about someone seeing them on ebay, but I thought I also read that the connections were different. Do a search in hear for Uconnect. I have the aftermarket one also. Although it does not look as good inside, from what I have read in here it is easier to use than the factory one.
Yes. You can buy the U-Connect mirror. What you can do with it once you have it, I don't know. I am sure the car must be wired for it and I doubt the wiring is there if it wasn't ordered from the factory.
If you can do this why do they put the other system in our cars? I know they made that one first and it's for car not "pre-designed" with it in mind, but the LX has it designed in mind so IMHO they should install it just like the factory. Leave the other version for the Jeeps and such.