How much you update a "vintage" bike is up to you. That is an advantage from starting from a bare frame and building as you desire.
I've successfully built a 9s wheel using 126mm dropouts and an "Off-Center/Asymmetric" rim. And, presumably 10s would work to. But, a lot of people suggest just cold setting the rear triangle.
I'm a big fan of modern "aero" brake levers. Origin 8 Classique, TRP, Tektro, Cane Creek, etc. My biggest problem was that I lost the brake adjusters when I removed the long worn out Universal levers. But, one can add inline barrel adjusters.