I don't have an FTM database and I've obviously never imported an FTM database into RM. So I don't know where media from FTM is attached in RM. However, I think I can provide a little useful information about how media works in RM.
I think it's obvious, but it should probably be stated anyway that RM does not store any media in its database. Media in RM remains in whichever Windows folder it was already in and all that RM does is store a file string to access the file (the file name and the subfolder structure under which the file is stored)..
Media in RM can be managed in either of two directions, and the two directions are not mutually exclusive. For example, you can be managing media in the media gallery and you can tag a photo of a grave marker to a burial fact. Or you can be in the Edit Person screen managing a burial fact and from there you can connect the same photo of the same grave maker to the same burial fact. Having done so, the media is equally well "connected" or "tagged", after the establishing the connection you can't even tell which of the two ways was used to establish the connection.
Media can be connected to a person, to a fact for a person, to a Master Source, or to a citation of that Master Source (and actually, to a few other things as well, but this list will do for now). A citation can be connected to a person or for a fact for a person. That raises the question of where is the best place to attach media. For example, is it better to attach a photo of a grave marker to a burial fact, to a citation for the same burial fact, or to a Master Source which is a part of a citation for the same burial fact? There is no one best answer for all users, but a new user should understand the possibilities and make informed decisions about which approach (or approaches) best meets his or her needs.