I have some questions about the fuel efficiency of various A/C options.

1. Does it make a significant difference to fuel efficiency at what speed the fan is running?
2. Is fuel efficiency significantly affected by turning on or off "recirculate"?
3. What does "Max A/C" do? I though it just turned on recirculate, but since I've seen people say not to use it, I'm not sure.
4. Why is that "Max" A/C is not available with ECO mode on the TCH?

The basic theme here is that I thought that simply whether or not the A/C compressor is on far outweighs everything else - fan speed, recirculate, max mode. But given #4, I'm not sure any more.