Backwoods Sleuth, or any other familiar with ebook files on a Kindle.

Gotta ebook question for you. I may need to test a mobi file of a book but I do not have a kindle. My brother has one. Can you load a mobi file into it, or is downloading it from Amazon or another site the only way?

If I send him a file attached to an email, can he load it off his PC though a physical attachment like a USB port, etc.?

I have no experience with them.