I'm building a wall shelving unit. It's going to be pretty big, about
4' tall and 13' long. It will hang on the wall in the family room,
touching the ceiling.

I plan to build it as 6 separate bookcases. The shelves and uprights
will be 3/4" oak ply. I plan to make a "face frame" if that's the
right word, of oak 1x2. I may or may not put full backs on the units.
There won't be any doors.

My skills are modest. I'm a reasonably capable homeowner/handyman, and
I've built a few simple pieces before. In building those pieces I have
found that the finishing, even with my very basic methods, is a LOT of
work.

This project is much bigger than anything I've done before and I'm
afraid the finishing will take forever. (Did I mention that I have a
job, a house, a family and limited spare time?) In addition, I found a
stain that I like, adding another step (or two) to the process. Since
the units will be built-in, the outside surfaces won't need to be
finished, except for the bottom, but that still leaves quite a lot.

So, finally, here are my questions:

I'm considering finishing (or partially finishing) all the pieces
BEFORE I assemble the actual units, so I don't have to apply several
coats of "stuff" to a couple of dozen inner surfaces. Since I'm going
to use dadoes and none of the outside surfaces will show, I'm even
considering assembling the units with screws (no glue). Does any of
that sound like a bad idea?

I've tried out the stain already and I like the color. I'm wondering
what to follow it with. I have used a couple of different kinds of
poly on previous projects, with passable but unexciting results. I
think I'd like to try some sort of oil finish this time. Will this
change the color a great deal? I'm looking for a low lustre finish.
Will I need to sand in between coats of oil like some other finishes?
Would it be better in any way to apply the LAST coat AFTER I assemble
the units? (I'm thinking that might help to fill in the edges at the
joints).

I want the project to come out nice, of course, but I'd also like to
enjoy using it before my old age. My wife concurs, strongly, with that
idea. Any suggestions that would help achieve both those goals would
be appreciated.

Greg Guarino