1) How hard do I have to jerk on that oxygen mask thingie to get it to flow, without pulling the hose off?
When the masks are deployed, they are hanging from a bit of string (at least in a B737). In getting the mask to your face, pulling the string releases a pin, which starts the chemical oxygen generation. There is enough slack in the actual air line so that you will not be tugging on that to get it started.
Photo;
photo credit from:
http://en.wikipedia.org/wiki/Image:P...k_dsc06035.jpg