OSMC (Debian based), if you want to install additional software or LibeELEC if you like to use only Kodi.

I know, but NK politically isn’t that far away from PRC.

I recall a statement from an article I’ve read several years ago on the presentation of Will Scott, a professor who has been in NK, at 31C3 2014.

Als sich Scott Root-Zugang verschaffte, fand er ein für Normalnutzer unzugängliches Programm, das die komfortable Einrichtung verschlüsselter Datenträger erlaubte. “Das ist interessant, wenn ihr einen AES-verschlüsselten Datenträger braucht, an dem die NSA garantiert nichts manipuliert hat”, scherzte Scott.

When Scott gained root access, he found a program inaccessible to normal users that allowed the convenient setup of encrypted data carriers. “That’s interesting if you need an AES-encrypted data carrier that the NSA is guaranteed not to have tampered with,” joked Scott.

Red Star OS ftw.

You could still enter the URL manually if you are concerned.

It depends. The seller may note a device ID, e.g. the IMEI of a smartphone, on the invoice.

Everything.

According to Wikipedia, wireless USB should be secure too: “The goal of the specification was to preserve the functional model of USB, based on intelligent hosts and behaviorally simple devices, while allowing it to operate in a wireless environment and keeping security on a par with the levels offered by traditional wired systems.”

If the keyboard is connected via Bluetooth, it should be quite secure.