The Kindle can read PDFs, but it's not an ideal format - it shrinks each page to fit on the screen, so unless your page size is fairly small, the text is likely to become unreadable. The user can zoom in, but they then have to scroll around the page, which is very cumbersome and likely to result in a bad review.
The main Kindle formats are .mobi, .prc (this is an older one, not used much nowadays) and .azw (which I think is just a DRM'd version of .mobi, so you can ignore that). If you don't already know how to generate a .mobi version of your book, follow cathugger's instructions.
Don't send the actual book unless the reviewer has told you that they'd like to receive it, or their website says they don't mind receiving unsolicited books.
(And yes, sending an ePub file to someone who has a Kindle will **** them off. Kindles can't read ePubs. Calibre and other programs can convert ePub to .mobi, but reviewers don't look kindly on authors who expect them to do work that the author could've done.)