OK, but if you remove the corn subsidies from the REAL price of corn and THEN compare the cost of alcohol made from corn does it really pencil out that much better than alcohol from biomass?
How about selling that 40% of corn production on the world market instead of making ethanol out of it. How does that affect the equation?
Even if it pushed the price down temporarily, I'd think the market would achieve a balance pretty quickly. Unfortunately there isn't a market for plant waste - so it goes to waste - whereas the corn wouldn't - it could be sold. The leftover stalks and leaves from the corn could even be a good portion of the waste plant matter used to produce alcohol.
If the market for corn is down, grow something else! That's what my grandfather did for over 60 years. He switched his main crop several times that I can remember. Corn & hogs, hay & cattle, hay & horses, soybeans, oats, whatever paid best at the time, that's what he raised.
The other question that comes to mind, is how much more does it cost to transporting biomass - like switchgrass or corn plant waste - than transporting grain? I'm not seeing how that is a significant factor either way - especially when the plant waste is free or nearly so.
Basically, the main point that I'm getting from most of what you posted is that corn was chosen as the alcohol production feedstock for reasons other than what was most practical.
Seems to be the way too many things "work" in the modern world.