I'd just add one thing: the yellow arc on the MAP instrument shows how hard the engine is working to maintain rotor RPM. By implication, then, it shows how much rotor-blade drag is being overcome by the engine: the higher into the yellow you are, the more pitch is on the rotor blades. So, the farther you are pulling into the yellow, the faster your rotor RPM will decay after an engine failure.
When you're up in the high yellow, get really spring-loaded on that collective!