Hi There,
Thanks for the interest.
1. Check out if keyboard you want to use Teensy with is present in Keyboard list of Arduino (with Teensyduino installed) I can see French Belgian is supported.
2. Sorry, no user guide yet. You may find Kautilya quite easy to use without a user guide too.
3. I am travelling and may soon put up some videos once I have some time. Meanwhile, keylogger is there in the payloads menu. It is a powershell based keylogger and will paste keys as a private paste to pastebin for the account info you enter. Please let me know if you want any clarification on this.
Cheers,
Nikhil