It appears everyone at this incident has an awareness of pedestrians and traffic; yours as a cycler, is heightened.

In reading your account I'd observe that the car behind you as well as the second car stopped because continuing through you would be hazardous to you. You were in the street. The pedestrians were getting ready so they were off the street at the time. They were probably watching you and concerned.

I'm reminded that Toronto has pedestrians hand-signal their intent to cross a street prior to stepping into lanes when traffic stops. If there's a similar practice in place in Michigan I'm not aware of it; however, I'd support one.

I gave the first pedestrian a sign to indicate my intent to stop for him, but he was very hesitant. So I had to come to a full stop. That must have irritated the car driver behind me, because I was in the car lane, not the bike lane. If I am in the bike lane it is completely useless to stop for pedestrians, because the cars will never stop (based on experience). But the reason I am in the car lane is that I am moving along at the same speed as the cars during rush hour, and this way I don't get hooked by cars turning right.

By the way, as a pedestrian, I often use a hand sign to indicate my intention to cross. Usually it works.

Per MSU ordinance, drivers only have to stop for pedestrians already in the crosswalks, not on the curb intending to cross.
ordinance 32.02 approved by Board of Trustees:
.02* Pedestrian's right-of-way at crosswalks: Where traffic control signals are not in place or in operation, the driver of a vehicle shall yield the right-of-way to a pedestrian crossing the roadway within any marked crosswalk or within any unmarked crosswalk at an intersection, except as otherwise provided in this section.

http://trustees.msu.edu/ordinances/ordinances_sec32.html

It can be frustrating with mixed use roads, but people are asked to use courtesy and common sense. The drivers you mention were guilty of incivility for sure but not a traffic violation.