The $0.10 email is email@example.com
. The free one is firstname.lastname@example.org
. You get both when you register your Kindle. I'm not sure about the Mobi software, but the Kindle does not currently support DRMed PDFs. I don't know if there's a stand-alone reading device that currently does. IIRC, there isn't. I don't know what Amazon's plans are. I've heard that both Amazon and Adobe may be supporting .epub in the future but it's anyone's guess at this point what will actually happen.