The back removes (but not the bottom), so in a way like a Nikon F, but not quite. It just makes it more of a handful to change the film in terms of juggling multiple things in two hands (camera, back, film, takeup spool). You slide a latch on the side of the camera and the back comes right off. You need to be certain, however, that when you put the back on the camera, that you catch the groove around the rewind knob on the bottom of the camera. If you don't, you'll end up with a nice light leak from the rewind knob not being properly secured! This is why I personally like the VX Version 1 -- it has essentially the same aesthetic of the Varex, but the hinged back makes life a bit easier.
As far as servicing and parts go, the cameras are generally inexpensive, so any parts can usually be gotten from other camera bodies. My repair fellow here in the U.S is Frank Marshman/Camera Wiz in Harrisonburg, VA, and he tells me that Exaktas are very easy to work on. Just this year he did a CLA on two Exakta bodies of mine, and replaced the curtains in another, so I can't imagine that service would be an issue. As you mention, the Exakta club would definitely be able to point you in the right direction.