First, congrats on the upcoming G10! I have that exact model and love it. Now, let's get this working for you until you get that new bad boy.
To watch the video from the VCR on the TV through the yellow composite video connection, you need to press the "TV/VIDEO" button on the TV remote (right-hand side of the remote, about a third of the way down from the top). That will cycle through the available video inputs on the TV.
As for the sound, there's no need to run audio from the VCR to the TV in order to hear it on the receiver.
Do you still have the owner's manual for the Yamaha? If so, page 13 covers how to connect a VCR and TV to the receiver quite well. If not, you can download it from the Yamaha website.
I'm sure that doesn't cover it all, so just let us know the questions that you have left.