I am about to take down quite a few metres (maybe 20+) of shelving.
This is all hardwood, though I've no idea which, that has been in place
for probably 50+ years. Although runs are interrupted for support,
spans are at least 1m, so there's some useful amount of hardwood there
in 7" x 1" boards.

I'm thinking of making a table top from this stock. The plan would be to
make 2-off 1m squares and (maybe) a 0.5 x 1m removable centre leaf.
Clearly, I shall have to source something for the legs and frame.

So - questions:

1" isn't really thick enough for a stable table top and probably too
shallow to biscuit joint, so I was toying with the idea of mounting
these boards onto sheets of ply, screwed in from below to keep
everything in place. Does this sound sensible?

Ideally, I'd like to curve the ends of the outer leaves. This would be
a simple (famous last words) task to cut, but there will need to be a
border around the edges and this would have to be bent into shape. How
hard is it to steam and bend a (matching or contrasting) hardwood strip,
which is something I've never tried before? (If this isn't going to be
reliable, pragmatism says it should be rectangular!)

With the best will in the world, although they look very straight by
eye, there will inevitably be some small gaps where boards meet. I'm
thinking sawdust from the timber mixed with some glue would be the way
to fill these. Any better suggestions?

Once built, sanded off etc etc, I'll need to finish the surface with
some kind of treatment, and there are many available. It would probably
look best with a good sheen at least, if not high gloss, so that
probably rules out oiling. I've always quite liked French polish, but I
wonder if there are any 'modern' alternatives that would perform as well
as this and give a more durable finish. There will be plenty of offcuts
to experiment with, of course.

Any answers or further suggestions, especially from experience, would be
appreciated.

Cheers chaps