You only have the 1 big c rib and not a set?

Is the C rib on the side that is most symptomatic?
If so, usually a slam dunk , if the c rib is removed (by an expert surgeon of course) many/most of your symptoms will resolve.
And the surgeon might find other issues that are problematic during the surgery - so an expert can take care of those at the same time.

Have you seen/tried the 'hands up/stick em up" test ? this is it - halfway down the page - kind of gives an indication if pulse is being closed off in that position - http://www.nismat.org/ptcor/thoracic_outlet/

useful sticky thread - tons of collected medical & therapy links -
http://neurotalk.psychcentral.com/thread84.html

nausea,
if pain is high I suppose it it could be due to that, but if you are very worried/stressed it is probably more due to that.
If on any meds those could be contributing.

yoga, running, cello - hmm I'd find non arm use/repetitious/static postures/jarring ways to relax
no use irritating things more than they are.

foam roll/inflatable ball/rolled up towels to lay on and let shoulders drop back/down, or even just the lay in the yoga corpse pose and relax and breathe. Gentle stretches to re balance if head forward/shoulders forward posture.