So, I need the subtitles patch and audio fixes. I've been browsing the threads about these but always end in dead-ends, 404 links, etc.

For now I used this for subtitles (no automatic .exe?): http://www.mediafire.com/?k1ia8wzr36u2qda

And these configs for the audio: https://www.gog.com/forum/gabriel_knight_series/any_suggestions_for_gk2_general_bugginess

But honestly I have no idea what I'm doing.
Does anyone have the correct and easiest way to install these things?

I don't know if the GoG version includes the original disc image files, but if yes you can mount them and use the installer from this website: http://gkpatches.vogons.org/

Using this I could install the german version (using original the discs) and play from beginning to end without bugs.

Thanks for the reply, but I'm not going to research if the gog version has the correct files. I need something that works 100% with the gog version.

I've been playing mostly without issues, I replaced the old PATCHES folder with the new one. But I still hear some audio crackles from time to time.

And I just got a crash after a conversation with Xavier on Ch. 3, will try again later to see if it has a 100% repro.