Thanks your your kind words and the long list of bugs. They've been brought up before and I've done my best to fix most of them. There's still a few stragglers here and there.
The re-appearing enemies are a very common issue that I have been unable to fix. They're not really respawned, they're just illusions. Think of them as just the angry, impotent ghosts of your foes while I figure out a way to fix that.
As for the drones, they are not the only ones enslaved by King Sombra. Each level holds even more slave ponies. What you just saw was a handful compared to the rest.
And I'd gladly accept help if needed, but I don't remember who you are on derpibooru?