Is it possible to ignore default styling when dragging from the structure pane into an element? I'd like the content from the dragged entity but to keep the style already applied to the target element. It would save me a lot of time each week if there was a magic undocumented way to do this. Anyone?
in the edit menu There is a "Paste with formating" option. In this way, STYLE does not come in COPY / PASTE operations.
Also, in each of your projects, add special code to the beginning of your project-specific STYE names. Like W6_Body Text, W6_Header Style. W6 becomes the project codename. Even if styles come from different documents, when you delete them, InDesign will ask you which style you want to use instead. It gets easier to manage.