To the OpenAL thing:
I asked on the OpenAL talkboard and it is allowed to put the OpenAL32.dll and wrap_oal.dll into your project folder => then no installing is required. I will offer the dll's on the download page of ANet.

It's also possible to run the installer of OpenAL in "silent mode". In silent mode, no dialogs or messages will be displayed => you can easily start the installer from your gameinstaller or you could start it from your game (if it runs the first time on a machine).