Thank you for your compliments.
1) If the fuel injection is advanced too far, the Peak Pressures will be excessive at full power, this could start leaking around the cylinder head, mechanically overload the cylinder head bolts, pistons, connecting rods, crankshaft and bearings causing severe damage to the engine, however, what you are trying to do is correct the slight injection delay caused by the worn fuel pumps. This is why it would be best to check the fuel injection timing by studying the power/Draw card for the engine from when the engine was new with ones taken before and after any adjustment to the timing. If the start of injection was adjusted to be earlier than designed it would cause knocking. The old check to see if the barrels and plungers are worn was to strip down the pump, make an airtight seal over the end of the barrel /Plunger unit with the palm of the hand and turn it upside down, the plunger should be held in place by the vacuum between the hand and the plunger, if the plunger drops out, they are worn out.
2) & 3) The Governor will try to maintain the engine at constant speed, if the fuel pumps are worn (and therefore delivering less fuel than they should in relation to the fuel rack position) the governor will compensate by increasing the fuel rack setting until the engine produces the required amount of power to maintain the set speed. However, the fuel pump leakage will reduce the rate at which fuel is injected into the cylinder, increasing the fuel rack position means that fuel will be injected over a longer time/crank angle period, so the efficiency of the engine may be reduced. The peak pressure will be lower but the pressure will be sustained further down the expansion stroke, so that the area under the curve (power developed) will be the same as it should be.
4) I would not try to advance the injection timing to give a specific peak pressure, the "notch" on the pressure curve of the Draw card indicates the point of injection, I would only advance the timing sufficiently to correct the injection delay caused by the wear. Correcting the timing should, if everything else on the engine is correct, slightly reduce the Exhaust temperatures.
5& 6) Most modern fuel pumps are fitted with 2 spring loaded non return valves, the larger one, with the greater spring force opens to allow fuel to flow to the injector and closes at the end of the delivery stroke, the other opens at the end of the delivery stroke and releases the fuel pressure in the H.P. fuel pipe and injector, to prevent " dribbling" from the injector. On some engines the smaller valve is actually mounted inside the larger one. It should be fairly easy to test if these are opening at the correct pressure, and closing tightly, unfortunatly they are often sealed units (especially on Medium speed engines) that can not be dismantled and lapped in. If the Non Return valves are leaking this can reduce the volume of fuel delivered IF air is drawn in from leaking discharge pipe connections, or combustion gas leaks back through the injector during the pump suction stroke.
See the attachment from my ancient (1972) copy of C C Pounder's Marine Diesel Engines.
It is always better to ask a stupid question than to do a stupid thing.