For example, I can't understand, how to disable F-keys by default. And I can't understand why 0-window doesn't get new name if I started some program.
1 Answer
While not 14.04 specific, there is a quick-start guide available at http://j.mp/byobu-help, which does answer your "toggle all of Byobu's keybindings off" question, at least (hint: Shift-F12).
Your question here actually inspired me to write this blog post and create this 10-minute instructional video. Enjoy!
Full disclosure: I am the author and maintainer of Byobu.