One thing to try is put all the media you want to "manage" into a timeline, unless the media with your existing sequences is all you want to bring bring. Select the sequence(s) and go to AAF export. I am not in front of MC at the moment, but one of the settings in the export dialogue box is the ability to copy (not consolidate" media to a target drive/folder. Once that is complete, just bring the project and associated bins with you as well.
Sure it can certainly be made easier, but the "copy AAF" is one means to do that - especially in your case where different projects are associated with the media.
1. Highlight all sequences
2. Export AAF Link To and "copy media" to target folder
3. Ignore exported AAFs, just grab the media
4. Copy project and bins to bring with media
5. Attach drive and copy project with bins to wherever you like and start editing.
I selected master clips and did the same process and it copies those as well. So you can do both sequences and master clips. I did find some issues with audio tracks from the sources not coming over, but need to do more testing.
As far as the return, just bring back a bin of what is new, just the sequences most likely and they relink right back up.