here is a good resource for all the answers to your questions

http://www.nhtsa.dot.gov/cars/rules/import/FAQ%20Site/pages/page2.html

I would also ask the person who is selling the bike for any documentation he has on the bike. That may help clear some things up.

Being an NSR that was built for on-road use, it cannot be brought in as a perminant race vehicle, but can be brought in for temp periods.

I would ask for the NHTSA forms to see how it was brought in.
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Charles Gallant