As stated here many times, if your house is older, have a sample of the acoustic(popcorn) ceiling tested for asbestos.

After the removal of the acoustic, you might only need to re-mud and touch up the existing drywall. You can go another layer using longer fasteners and you will have to extend electrical and any ducting or other protrusions. You might want to check to see if the ceiling framing will handle the extra weight of another layer of rock. Personally i would just deal with the existing ceiling.

I see no need to scrape. I had a house in which the (dopehead) occupants packed heavy stuff in the attic supported only by the ceiling drywall. The trusses were 2' on center. The drywall bowed and cracked. Like you, I did not want to pull down all that blown-in insulation. So I used "strapping" (1 x 4 planks) 12" on center on the existing ceiling surface screwed into the trusses with 2 1/2" screws. I used a Tee-Jak to push up the strapping (and old drywall) tight against the truss. The new drywall went on the strapping. That dropped the ceiling 1 1/4" inches, not noticeable. The new drywall is much better supported and stuff in the attic should not damage the new since the strapping will support the accumulated "plunder".

If you need to cover over the ceiling rent a drywall lift.
The manual ones are OK for short use, the compressed gas powered ones are better for long term.