Range Cuts (also called Production Cuts) do not affect active tracks. They affect whether or not the EM processes create new secondaries, or whether they take the energy of those secondaries and add it into the “TotalEnergyDeposit” for a step.
No. If you have a track, it will be followed with all of its interactions, all the way until it stops (zero energy).
Approximately. There is a mean interaction length which is energy dependent. You can use that interaction length, and how it changes with energy, to estimate the “range” of a particle in the material, and that’s the relationship you see.
In Geant4, you specify a Production Cut (for gammas, electrons, positrons, and hadrons) in units of length. The code can then use that “universal” value and translate it into an appropriate minimum energy for each material of each volume in your simulation.