I'm amazed it's not better known. (Of course, the USA had to send an emergency repair crew to their own Skylab station when a bit fell off during launch...)
Re station-to-station transfers: Mir and Salyut 7 both had the same orbital inclinations (probably deliberately) of 51.5°; Mir's apoapsis was about 360km, Salyut 7's was about 250km. So a transfer would be relatively cheap. The vehicle was a Soyuz T only had about 320m/s of delta-V, which was also needed for rendezvous and deorbit, so it would have to be.
I think this was the only station-to-station transfer ever done. It was probably only feasible because they were in the same orbital plane.
(Although I'm a little surprised they didn't build Mir using Salyut-7 as a core module. Even if they ditched the module later as it wore out, it'd provide power, attitude control and automated docking.)