No problem,
If you can, I recommend you set XBMC to use the default audio device. Then you should be able to switch the default audio device that windows uses and XBMC should use whichever one you select. I don't know if this will be an issue for you or not, but hopefullly not because I dont' see a way to switch the xbmc device preferences programatically. You could get VC to open the settings window and then do a series of movements and selections, but it is not a good solution.
If you download the latest patch (0.879 from here:
http://voxcommando.com/forum/index.php?topic=414.msg2862#msg2862 ) you'll see that there is a program in there called setDefaultPlaybackDevice.exe
You can call this program using the launch command. It accepts a single parameter which is the name of the audio output device. You can call it like this to select the device named: Speakers
Launch setDefaultPlaybackDevice.exe&&Speakers
To see the names of the audio devices you can right-click the speaker icon in the notification area and choose "Playback Devices". There you will see a list, you can also rename devices here if that helps.
It should be easy enough to do the other things you want in a single vox command. If you are not sure how to do it yourself then try to give me as detailed as possible a list of what you want to happen and I'll try to help.
by the way, I created the program setDefaultPlaybackDevice.exe using AutoIT and modifying someone else's script that I found online. If someone wants to have the script used to generate the program just let me know. AutoIt is a pretty neat program and it's free.