The difference is in NASCAR the info must go through the driver to the crew chief. IIRC, the crew chief does not get the telemetry directly from the car.

There is not a maximum octane rating for the fuel. There is a minimum octane rating of 87 (RON+MON/2).

IIRC it was about $40 a quarter in the late eighties.

Hydrogen may be abundant but it takes a whole bunch of energy to get it into a useable form and distributed to filling stations. To me, it makes much more sense to go purely electric or plugin hybrid due to the gasoline infrastructure already being in place.