I have not bought them.
But from what I understand: Each miniature may be used on both games - AH as well as MoM. But I would not go as far and expect FFG to create all the game-stat-tokens for each individual creature of madness for both games, since most minitaures are not present on the MoM game, but are in the game of AH. I understand this product line as kind of an extension for all the creature-stat-tokens (those little square you may slide into the miniatures' bases) you already possess.
So I imagine that most miniatures, although in theory applicable to MoM, are basically for usage within your AH game. Maybe, but really just maybe FFG thinks about implementing more and more of the various creatures into MoM via expansions to come ... But I wouldn't want to bet on it ...
As about the knowledge about the creatures' abilities: Most creatures in AH or MoM are by far weaker then they are in the Call of Cthulhu RPG. Also the creatures vary between both games of AH and MoM at least slightly and are not comparable. Ergo it does not matter that you have not read the Lovecraftian stuff or Cthulhu Mythos based material and therefore lack deeper knowledge about the creatures of doom.
Another thing for me would be this: Are these "high quality" miniatures really worth it to expand your game?
All the best!