Don.
Q 1 There are two sight glasses each for port and stb up front of the settlingtanks. Q 3 Cock "e" shut the fuelsupply to the settlingtanks and is shown in shut position on plate 9.
Q 2 Fuelcollecting tank has nothing to do with the fuelsupply to the engines it is merely a collectingtank for the fuel drain and overflow pipes from the settlingtanks, filters,pumps etc . Fuel supply from the bunkertanks to the distribution box is drawn OK, from this box the supplyline goes to the distribution selector cock "e" which has 4 positions: A. shut to the settlingtanks and engines as shown on plate 9. B ,the unusual, daytank shut and fuel goes straight to the fuel supplypump on the engines,C topping up port settling tank and supply to the engine supplypumps from stb. settling tank and D, topping up stb settlingtank and supply to the engine supplypumps from port settling tank. See drawing below. Q4 The plate 9 shows more a MAN arrangement than a GW engine. On the GW engine the engine driven fuelsupply pump is up front of the engine. The "huge" pump bypass as you express it is normally shut and is only used when something is wrong with the pump. The relief valve has a normal dimension don`t get confused, look at the photos on the front of the engines.
Q.5 I am not sure if I understand your question right. If you mean the HP fuelpumps on the engines, the engine had to stop and a spare pump fitted, routine.
Tore