Hello Viktor!
If you don't rely on a GUI you could use grml at
http://grml.org
If you do need GUI, I'd suggest Debian from
http://www.debian.org
As to music software: I've heard that some schools use csound, which is
nice, because there are lots of ways to operate in non-realtime. I believe,
that Csound has GUI-frontends. Besids that there's CLM (common lisp music),
SuperCollider3 (SC3), which I think comes directly with a GUI.
For recording software, best completely rely on someone else's feedback.
I hope that helps!
Kindest regards
Julien
--------
Music was my first love and it will be my last (John Miles)
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