HNF2K-
YOu can get these rfom several online suppliers-- do a search on google for 'walking batfish'
I cant tell you directly- the post will get deleted or edited.
As for your tank size- should be ok, as long as you have large areas with open sand. Just keep in mind, these are reef safe 'with caution'. they will eat smaller, slower moving fish.
I have seen them at our LFS- they get them in from time to time- one of the coolest fish i've seen.