the AT-AT pilot in the movie looked different from some of the ones on the net. The one that blew the shield generator in the movie had a black uniform with his face visible. But some of the other pics I have seen show a Imperial TIE pilot's uniform, but with different coloring.
no he was just an officer, the drivers are already post here on the forum together with the at at and looked a bit like stormtroopers
I'll make a royal guard one, and yes I checked, you were right about him just giving orders. There were two pilots on the ATAT, and he was just observing