It has been shown during the course of the show, and various publications, that there are actually three shuttlecraft hangers; the main Shuttlecraft hanger is located on the topside-rear of the primary saucer section. This hanger is as large as a football field, but due to budget concerns, was never seen during the series. There are two, much smaller shuttlecraft hangers located on the Secondary hull portion of the ship. All scenes shown during the series take place in these hangers.



There were three generic Starbases shown during the run of TNG: the Space Dock from the third movie (Star Trek: The Search for Spock),  various redresses of the Regula 1 station from the second movie (Wrath of Khan), and re-use of the opticals of Farpoint Station from the pilot episode.



It could be successfully argued that Starfleet IS the military branch of the United Federation of Planets. Defense of the member planets is conducted by Starfleet vessels. All offensive actions undertaken by the Federation is done using Starfleet vessels. It has been shown during the era of "Enterprise" (pre-Federation) that a detachment of Space Marines was added to provide support for off-world activities.