Noreve makes Hanvon N520/526 leather cases (a bit expensive, though). http://www.noreve.com/langue/en.html
Since Elonex EB511 is Hanvon N520 rebranded, it should fit perfectly.
Regarding pdf, I think Sony PRS300 handles them much better than Hanvon N520 (I have both). I think that Sony 300 is the best 5" choice if you want to read a pdf - by landscape mode.