Too higher bleed requirement from the high stage bleed valve resulting in high bleed/ duct temperature.
The oil pump is a simple spur gear driven by the main gear box so it's output is a direct function of engine speed. On the ground the low idle may not have enough speed to achieve the output, in flight the flight idle should be enough to always achieve 13 PSI, unless there is a failure in the system hence the shutdown below 13 PSI.
The PMC is simply a fuel trimming device, the MEC provides FF for thrust lever angle and the PMC trims within a small range (3%) for accuracy.