If you don't want to force a specific wallpaper on users, you may have to do things a little differently.
Perhaps you could set BGinfo to use "%userprofile%\wallpaper.bmp" as the background image, and then any user who wants a custom image could save the desired background image in their profile folder.
Regarding pulling the existing wallpaper settings, you would have to test it and see.
Then, in the config file for bginfo, I have it set to use a specific bmp file for the background, and stretch it to fit the screen resolution.
That way the wallpaper is actually created and set for full screen based on the resolution of that user's session.
I've ran an RSOP and the machine is receiving the script on startup but its almost not running it?
I've amended the GPO Script path to %logonserver%\Netlogon\and it still doesnt seem to be running it at startup?