I have cut racks down. Cutoff wheel on the rotozip works fine if you are in a pinch and do not have anything else. :)

As far as the racks and wire management, the center support might be an issue. Is there any way to re-do the doors so there is simply a stop at the top and bottom and the piece in the center is attached to one of the doors? It looks simpler than I explained it probably. :)

I have mounted slide out racks side by side a couple of time. I usually keep a service loop that allows and pretty much requires both racks to be pulled out. Then you spin them both opposite directions, one slightly ahead of the other, until the backs are facing each other at whatever angle the rack allows...not 180 degrees from one another....but maybe 120 or 130? That center piece will be a biatch to work around though. Not impossible....but not happiness inducing. ;) Also, if there is no room on either side of the racks, make sure you plug the power cord in first! And anything thing else that attaches to a wall plate....you do not want to forget something because you will never reach back there again without cussing.