Thank you all for the advice. I ended up getting Kindle with cover. My son claims he can really take care of it as long as his 5 year old sister doesn't touch it
, and if he reads at least 30 classic books with it, it's already not a loss.
After looking at Kindle's screen by myself, I couldn't go for anything less good. For the password, I meant per book password. This is probably not supported I guess. I'll have to figure out how to keep my contents from my son. Maybe frequent upload-read-delete?
It looks some hacking activities for K3 is already rolling. Even better news to me.
Now, to hunt for books to read!