Regarding:

Q3: I assume my US issued driver's license will allow me to rent one of those very nice looking rally cars?

Yes, I've rented in multiple European countries from Sixt (looks like the BMW shown in the photo is from Sixt) and Europcar using my US license.

On my first trip to Germany I rented a car at the Frankfurt train station and went to my local AAA in the US beforehand to get an international driver's license (a translation really).

That turned out to be unnecessary as all you'll need are your US driver's license, credit card and perhaps your passport.