Hi Ben,
I am thrilled! ABS will take good care of you.
The H4D is great for copy work, simply because you can control all the functions from the computer, including the focussing. Very useful if your copy stand height is very high!
Enjoy your time at the library.
David
Ben, to add to this ...
When you are testing, have the dealer demo the sound feedback/graph focus aid. If manually focusing at the camera, you can actually hear the frequency changes as you refine critical focus. While I rarely ever have needed this and haven't for a long time, we did use it to calibrate and shim my Rodenstock and Schneider view camera lenses for use on the Rollei Xact-2 that I sometimes use.
I can also attest to the focusing at the computer feature using a simple toggle buttons which I do use very often in studio shooting ... it focuses in micro-steps as much or as little as you want.
RE: lenses ... if you get a 50mm be sure it is the latest version 2. BTW, the crop factor of the H4D/40 is 1.3X, so take that into account.
IMO, if you can afford the HCD 35-90 zoom, you would not need any other lens for your application, and wouldn't need to change camera height to accommodate various sized subjects which would allow you to fill the frame for every shot using live view as a guide. This zoom is as good or better than any of the fixed focal lengths it covers, and the zoom doesn't drift when pointed downward (at least mine doesn't). See if the dealer can have one for you to see as an option.
Best of luck on your choice whatever it ends up being.
-Marc