You could try to download calibre (if you don't already have it) and convert a couple of books and see how it works.
Here's another good thread:
https://www.mobileread.com/forums/showthread.php?t=39165
As for button layout, it's easy to feel the buttons on the Sony 505, and the Kindle aren't too bad either. The Hanlin V3 would be a little worse, but one could glue on small bit of something in a distinct shape, such as 2 or 3 layers of sticky vinyl.
BTW, except for text-to-speech on the Kindle, (which is surprisingly good), I don't think it has any other extra features that he could take advantage of in comparison with the others, as dictionary lookup and manu items are smaller size text.