.ogg files are just audio files. There is nothing special about them. They are like .mp3 or .wav or .midi files... just another audio format.

You should be able to play them with most good audio players. I can play all the VV3 files with my media player and also the free audio editor Audacity. If you click on them and are told that your computer doesn't know what program to use to open them, try starting up your audio player and opening the files from inside it. Or just download Audacity, it's an excellent piece of software.

Editing the in-game sounds is easy. Simply take the file you don't like and delete it (I suggest keeping a backup, of course). Then take a file you like and name it the same thing as the deleted file. Make sure the file extensions match, because while some files are .ogg, some are .wav.

Taking files from one VV game and putting them into another should be no problem. I tested it by replacing all the child voices with the bees buzzing sound. It worked just fine.

Good luck.