The question: What's an 'M' blower?
Adam I never heard the expression 'm blower' However the Merlins were supercharged,and not normally aspirated. The super chargers did have an 'M' gear and an 'S' gear, which in ' S' gear ran faster to compensate for the drop in air density with altitude. So at low altitudes 'M' gear was selected. Should electrics, hydraulics, pneumatics fail then most items returned to a fail safe position, ready for landing. To clarify 'M' gear was always selected for landing. (I think, but memory ?)
Think 1900 would refer to amount of fuel loaded as 2154 gals = all tanks full.Or time >
With regard to photos of everyone, think it has been removed, and replaced with Sticky Photos of everyone sequel. It is difficult to access, does any one know an easy way.