Given your location and dictionary request, I think the Sony 650 would be ideal. It comes preloaded with two English dictionaries for definitions and ten dictionaries to translate between French, Italian, Spanish, German, or Dutch and English. Simply tap on a word twice and the entry pops up in a box at the bottom of the screen. Tap anyplace inside that box for the full page dictionary. Tap in the corner to close the box or page and you're right back where you were in the book.
The Sony will let you write notes freehand on the screen or there's on on screen keyboard. You can also highlight and export highlighted text, but there are some limitations with DRM encrypted books. The Sony out of the box uses collections to organize books.
Install Calibre and it becomes very easy to use these. Calibre is easy to use right away, but has a ton of customizing available to folks who think in code and like tinkering.
PRS+ was developed independently and is not supported by Sony, but it is easy to install and adds folder functionality to the collections that already exist.