I would recommend the
Kindle Paperwhite. You can buy most English/Spanish books they sell on amazon.com and amazon.es, by browsing those two sites to get inspired, then entering the exact title in your amazon.fr store. You will even save money on the foreign books in many cases (Enlish books cheaper on .fr than .com, for instance).
The PW comes with English, French, Spanish dictionaries and probably some more, and you can install more than one, so you can have a Spanish
and an English dictionary active, and the good type: Oxford and RAE!!
To look up a word, you touch it and select look up. Easy.
The best thing is that you can get a ton of free English books by checking out ereaderiq.com, and you can
sign up for a library card here in the US and, for a yearly fee, you can download books in English and maybe even Spanish and send them directly to your Kindle, no wires necessary. I read in many languages, and the Kindle is the best ...
BEST... in terms of multilingual content and multiple dictionary support.