Few questions about domain mapping

Quite curious about this mapping plugin.

– WIll this domain mapping be considered as content duplication in Google point of view?

– Can I use this mapping tool on a reseller hosting account(I have 2 nameserver IPs) How about a VPS?

– When visitors enter the mapped url(his-own-domain.com) in their browser, will the browser redirect the address bar to the original script(blog1.blogger.com) or visitors will still see a masked domain(his-own-domain.com) in the address bar?

Thanks