Who says they don't know? Scrooge McDuck has been doing this show long enough; he usually just provides the voices, but I'm sure when Disney showed up at his real-life mansion with a film crew, he knew what was up.
Launchpad might not have known what was going on, however. I hear he's been hitting the bottle pretty hard ever since they cancelled Darkwing.
Nah, if anyone was going to lose his shit it would be Drake. Launch Pad essentially was just a happy go lucky goofball who would be fine on his own. As is evidenced by the dark future episode where they part ways after Gosalyn time travels. Without her to balance him out, DW goes absolutely apeshit and just beats the hell out of criminals and develops his own fascist city state. Launch Pad goes back to being a mechanic and WHY DO I REMEMBER ALL THIS