[Sirtel]

For your need-to-have list, the Kindle Oasis, the Kobo Forma and the Kobo Libra are all suitable. None of them has anything from your optional list, though. I don't know of any device having all the features from both of your lists.

Kobo readers are very hackable and very customizable, without any need to root/jailbreak. Many hacks and patches are available here in the Kobo forum. The Kindle is not really hackable, but it is customizable to a degree (you can load custom fonts and custom font sizes on it). It's faster than Kobos, if that's important to you. Not that Kobos are terribly slow or anything.