Okay, as far as the finishing goes I use the Watco walnut oil and sand with diamond hand pads to 1500 grit. Progressively from 220 up. After 400 grit I am polishing the wood with oil. After that I just use wax, a couple of coats is all that is needed.
X-ray film that big will be done one at a time in a flat bottomed tray. I still have to make the hangers for the 11x14. Just haven't gotten around to it yet. You can get great neg's doing it this way. With my 8x10 I'm able to do four at a time in one gallon tanks. ULF is a different story.