With all due respect, read up in this forum, read the FAQs and stickies and such. Those will answer most if not all of your questions.
A RTW has to start and end in the same country. By studying your itenarary(sp?), it seems you're going to need a way home back to NYC. The speadsheet in the aforementioned sticky will tell you which country is the best to start the RTW in, if it's worth the hassle.