Wikipedia cites Mises as someone who developed the quantity theory of money. Is this in/correct?
http://en.wikipedia.org/wiki/Quantity_theory_of_money#cite_note-8
yes, there is a Austrian - causal realist approach to monetary analysis that considers the actions of individual actors and from this arrives at a quantity theory of money.
very briefly → http://mises.org/easier/Q.asp
Yeah, the QTOM is not by any means exclusive to Monetarism, in fact it predates it. Mises cautioned against certain uses of it but I don’t think he completely disavowed it.