the major resources for information on Z88OS are the manual (which is part of the repository), this board and the book (https://www.amazon.com/Finite-Element-A ... 1569904871
). This should point you in the right direction to get started with Z88OS.
Yes you can change the language to English if click on your name in the upper right corner, then "Kontrollzentrum" -> "Einstellungen" -> "Meine Sprache". I hope this helps