do any ships carry about marines for docking engagements? Even though its relatively useless in our era, the US Navy keeps contingents of marines on its vessels. Is there such thing as actual soldiers with body armor rather than crewmembers who have combat training? Also, does the ST universe use any tanks or armored ground vehicles? Or is this more or less useless as most infantry combat is small scale and wars are more or less decided in space?
From a non-canon perspective, FASA did include marines for both the Federation and the Klingons, with a lot of Klingon vessels having cryogenic systems for keeping troops in suspended animation until they could be used in offensive. The Klingon module Termination: 1456
also shows about half a dozen Klingon ground vehicles, although I don't know at present if any other modules included such units. Most typically used starships.
As far as the FASAverse is concerned, Starfleet is very much a standing military in the sense Crazy Eddie
describes - it's a professional military with training in exploration as well. What's been shown on screen has differed quite a bit from that interpretation, but one could also argue that differing eras brought different opinions on what sort of organization Starfleet should actually be and where its focus should be.