Super noob question about propeller controls

[NixonRedgrave]

Right here on our own forum:

[Advanced GUIDE] Constant Speed Propeller System

Introduction The purpose behind the constant speed propeller system is to achieve a high propulsive efficiency over a wide speed range. A fixed pitch propeller is only efficient over a very small speed range. A fixed pitch propeller optimized for climb will have good performance during take-off and climb (low speed) but during cruise the blade angle is too low. A fixed pitch propeller optimized for cruise has good cruise performance (high speed), but during take-off the blade angle is too large…

You can nerd out with me here, which lead to the aforementioned Advanced Guide:

Help Understanding Piston Engines w/Constant Speed Propellers

It’s very hard for me to admit this and swallow my pride given my massive knowledge as a builder of sports/racing car engines, but I’m struggling to understand some basic concepts surrounding the following: As I fly the DC-6 and, now, the Staggerwing, I’m trying to understand what, specifically, the Manifold Pressure and RPM indicators are telling me in regards to what the engine is doing and how that differs or is the same as to what the propeller is doing. Let me, first, put out my assumptio…