The prefix Inch- denotes island. Inchmahome is the island.Yes it does. Loch Inchmahome😉
Despite what wikipedia might tell you, Loch Inchmahome is a nonsense name. Lake St. Colmaig's Island? What?
Menteith is a weird one all round. To my knowledge it's the only freshwater body in Scotland that is described as being of something. Plenty of other geographical features are of something, but not lochs.