Your detailed response has been very helpful and I agree with your “copy not link” suggestions.
You say that the FTM Media folder is normally in the same directory as the FTM file it relates to, and this agrees with Tools>Options Help which says
“Default directory for new tree files:
Designates the folder on the computer where Family Tree Maker creates the tree files and media folders for your trees”.
However, for me the Media Directory is created in the separate C:\ drive or Working Directory by default, even though I have attempted via several trials to re-set to a Custom (Dropbox) Directory in Tools>Options.
So this is my precise problem. Tools>Options allows a default directory to be set up for new FTM Family 2012 files, which are small as you say. But the Media files are in a different directory.
As you suggested, being able to put the whole kit and caboodle in my Custom (Dropbox) folder is essential for syncing, but the Media files always revert to C:\drive.