Can't answer the last part. Assuming the fuel is similar, I would think no effect on heat range.

re Jetting. If the density is signficantly different, the amount of fuel (mass) going through the restrictions will be different. The volume passed will be the same but the mass change changes.

I don't know if that's more important than the Stoich ratio, which also varies. If you look at the Sunoco's or Vp's specs, you can see the stoich varies as well as the specific gravities. On average, we can pretty much assume our street fuels with eth have stoic AFR rations less than 14.7 to 1.

For the guys (gals) looking for the last drop of power or consistancy an advantage of racing fuel that all the properties are published and consistant.