I have mild symptoms of both neuro and vascular TOS, though the symptoms of the latter are more pronounced.

Anyway, two months ago, when I did not know anything about TOS, I thought these symptoms were being caused by a slipped disc. So I did a few back arches for that. I didn't feel anything immediately after the back arches, but half an hour later I had extreme tingling in my right arm when I would raise it. I also felt some crawling sensation in my face.

What could it mean? Could this be taken as a test for TOS? Does this mean I definitely have TOS?

It was probably due to the position of your arms that brought on the tingling, maybe the nerve/muscles/fascia got over stretched/irritated when doing the arch.

In the Useful sticky thread , there is a post with testing info. The whole thread is full of crash course info on TOS -
http://neurotalk.psychcentral.com/thread84.html

This happened to me doing the cat arch thing and why I stopped going the foam roller. Not entirely sure why but if one areas ****** it starts a chain reaction

i actually read in a pt forum that some girls hands became less numb or painful (???)

after being able to stretch her midback which is why i tried it to begin with but mine is stuck.