Hi. I have had the Sony PRS-650 for two months now and am very happy with it. Yes it comes with 12 dictionaries including the French-English and English-French dictionaries. It is very easy to use too as it is always on after you have selected it. Just tap lightly on the word and a widow appears at the bottom of the page with the definition or translation.
It is not perfect in the sense that if you tap on the word "l'occasion" it will say "word not found" because there is an l and an apostrophe before the word. The way to get around this is to open the keyboard and delete the offending letter and apostrophe from the beginning of the word. The same goes for words like "s'occuper" etc.
To buy French ebooks try the following sites for a start.
(80 000 titles and 750 comic books)