In article ,
I'm interested in the same questions, but further to #1, I was
wondering if anyone can post a complete-idiot's guide to using
portable oxygen in an airplane:

Maybe not exactly what you were looking for but:

http://www.avweb.com/news/columns/182079-1.html

I can say that medical O2, welders O2 and aviation O2 all come off the
same tank, so they are exactly the same product. I don't know if the
various tanks or eqp used have any affect on flow/use thou.