RE: Receiver Battery need foam?
I've got to agree with what Geistware said. Vibration is a killer. When it comes to batteries that translates to solder joints failing. I wouldn't risk it, considering how easy it is to prevent it. If you're cramped on space there is a trick I've used before. Get a computer mouse pad. They give quite a bit of protection without taking a lot of room.
Hope this helps.