1. You are right...if the protestors block streets, they should be arrested. That's part of protesting. If you are not willing to be arrested for your stance, then are you really taking a stand?
2. I may be wrong, but purposely driving through a group of people in the street is a crime. Now, if that is the driver's way of taking a stand that he should be allowed unimpeded access to the road, regardless of human life, then he, too, should be willing to pay the consequences.
I'll bet the "protestor" in #2 will face stiffer penalties, though, and he should.
(BTW, in your advocacy of #2, did you consider the possibility that one of the protestors in the street could possibly be holding an infant? If you were the driver, and the child was hurt or killed, what would you say to the parent? "You shouldn't have been there! It was my right!" Somehow, I doubt it.)