For the reflection you can use a peice of plexiglass the hardware store. And yes, if you want real white, they had to be far away and you have light put a lot of light right onto the background. If they are to close, the light will reflect from the background and they get a bright rim light (which can...

I'd say put your subjects at least 6 or 7 feet away from the backround... and to have an even, pure white background you will have to put up some lights that are aimed at only the bg. Keep shooting! Alicia