The WC4 GoG release always crashed for me when trying to launch the game - the problem lies in the infamous ms data execution prevention (the same thing is causing problems for Silver). I hadn't found this one mentioned in the other threads so in case anyone is having the same problem: control panel - system and security - system - advanced system settings - advanced - performance - settings - data execution prevention - and here you add the exception for wc4dvd.exe.

Installing the ac3 filter solves the sound issues.

For further problems, this seems a nice guide:
http://www.gog.com/forum/wing_commander_series/nz17s_wing_commander_4_get_running_guide