Nice Professional, I always forget how nice they are until I see one again.
brake cable should be availaible from almost any bike shop, what you want
is standard cable housing (white) and while you're at it new cables wouldn't hurt.
From the posting I'm thinking you don't have a whole lot of experience working on
bikes so I'd suggest finding a good maintenance book. You could check ebay for
'period correct' books.
probably need bearing repacked eventually too, a good book should
take you through all the required steps.
As for the rust start with Oxylic acid paste (do a search here, lots of threads)
to remove what rust there is, it also won't kill your paint. Wash your bike.
once you get that done apply nail polish (or Testors paint) in a color close to what you have
over any bare metal, and then wax the frame with a good auto wax. Simichrome polish for
any chromed bits (be careful on the Campagnolo anodized aluminum).
then ride it while you slowly ponder what to do with it.
I'd stay away from powdercoat, unless you're using someone who is
very experienced with working on bikes, like Spectrum Powdercoat.

oh yah, almost forgot, welcome to Bike Forums especially the C&V (thats cranky & vintage!)
sub forum.

Marty