There are two main reasons you saw the numbers you did. One, is latent heat of vaporization. Ethanol cools the air a lot more as it evaporates than gasoline. Cooler denser charge = more power. Two, is even though the energy content per amount of ethanol is lower than gasoline, the stoichiometric ratio is also lower. So you're using more of it to burn the oxygen in the air. So, even though the energy content is lower, more of it is going into the cylinder, and if you figure it up you come out slightly ahead in terms of energy per combustion event.

Propane is already vaporized, so it doesn't cool the intake charge at all. Now if someone found a way to inject liquid propane...

Something else to note is that the oxygen in the ethanol molecule is not available for burning. It, in a sense, has already been burned. It is just along for the ride, so to speak. This is why the stoichiometric ratio is lower than gasoline, not higher.

Also note that the higher compression ratio increases the efficiency of the engine. Where ethanol has an advantage, as already stated, is it allows you to run higher compression ratios. So even though ethanol has a lower energy content, you can extract more of it per unit of ethanol if you run higher compression than you can gasoline. To what extent I'm not sure though.