1) You need windows.
I bought Parallels and use that for booting a virtual windows machine. For the most part I just browse the sony store in Safari and if I can't buy the same book for the same price at Fictionwise then I'll launch windows and buy it that way.
2) Just play with it. I use it for maintaing my library, tags so I know what I have and haven't read, rating's, etc. Like Andybaby I don't use it for converting though, as I also prefer to use Bookdesigner under windows for that.