Can you attack the same front twice during the same turn? If yes, does the DRM apply to both attacks?
Yes and Yes (this is different from WMTtE where a Front could only be successfully attacked once per turn).
On Convoy card turns, take note to keep those DRM markers in play as they also apply to your "Free Action" should any part of the Convoy arrive safely. Once that occurs, then remove them all from the map, as normal.