The following statement is NOT true: If the quantity of money in existence increases by a factor of X (say doubles), then all else being equal, its value relative to goods and services will decrease by a factor of X (value cut in half).
Sorry this is nitpicky, but that statement IS true if one really "holds all else equal." By holding all else equal, one is cancelling out price elasticities and time preferences and thus a doubling of quantity would equal a halving of price.
However, in the real world one can never hold all else equal, so it's correct to say that just because money supply doubles, it does NOT mean prices will double. This is because price elasticity curves are not linear, they are curved - and people will thus behave in a predictable, but not linear, pattern.
But I concur with your general sentiment, OP