Well i would say Running back...in an 80 yard dash can u run a 10 Flat?
If your fast: cornerback or wide receiver
Anyone you choose! - Most coaches would have you on the line
Punter or placekicker. No speed required.
In 7th grade you would probably be an offensive or defensive lineman.
cornerback or safety
wide receiver if ur fast...goodhands. safety if not maybe cornerback