As to the origin of the Skeksis, The Dark Cyrstal and Dark Crystal: Age of Resistance seem to agree. In episode 7, the Heretic and Urgoh put on a puppet show explaining the origin of the Skeksis and Mystics, and it's essentially the same: that the Skeksis and Mystics were once one as the UrSkeks, and they need to be re-joined.
As for the Skeksis that ...
While the Super-Mobile is primarily a pre-Crisis device, it's made a couple (semi-whimsical) appearances post-crisis, mainly as meta in-jokes
From Wiki -
A few different versions of the Supermobile are seen protecting a
futuristic Ivy Town in All-New Atom #8. The classic design of the
vehicle can also be seen atop the sign of Funky Flashman's used