Selecting multi segment edge and more

 From:  FelixPQ (FELIX)

is there a nice easy way to select a multi segment edge (connected) from a solid like the red edge segment (copied and colored) in the file I've uploaded. After selecting this first segment, maybe use some script or command to select all connected edge to this one. It would be nice also to be able to kind of "join" or "merge" these connected segments as a single edge (not a regular joined copy) and maybe give it a name separate from the solid if needed.

Though in this case it's easy to pick all connected segments and apply whatever command one's want I'm sure there are many case where it would be easy to miss a few tiny segments. I'd be happy to just be able to select all connected edge with a minimum of work.