As answered, with the current Eink technology backlighting is not possible. You're pretty much stuck to reading lights for now.
As for document conversion, it really depends on the type of documents and the reader you want to buy. The iliad has a larger screen so things are more readable.
PDF can be read, although at a lower contrast. You can go to here for some example pics and reviews
http://hightech.afmag.net/
The iliad is more "open" and has more programs available for it.