I have never purchased a RTW ticket so I can't help you much there. But you did not mention visiting either of the Americas in #17 so perhaps a RTW ticket is not in your future.
I know that many countries (it used to be EVERY country) require "proof on onward travel" as a visa or visa waiver condition, so at the very least you'd have to plan your stops 2 or more at a time. Sometimes the rules are relaxed if you enter by ground instead of by air.
Hosteling is easy in NE and much of SE Asia, just buy the Lonely Planet guides as appropriate and go. In western Europe its even easier, almost as easy as getting of the train and asking friendly strangers.
