Drywall – How to hang drywall from a ceiling made out of aluminium insulated panels

Option 3 is the sanest IMHO. You can get a bucket of drywall mud for $15 and do a "skim coat" over the panels to create a flat surface. No need to sand first; this stuff will stick to anything! Once the mud is dry, you can sand it to get a smooth look, or texture it. Texturing can be done with cans of spray-on texture you get at big box stores, or using a texture sprayer gun. A pro will be able to do the texture part much better than a novice, so if you want a textured wall, I recommend hiring that part out for $100 or so. With the right equipment and an operator of moderate skill, it's a 30 minute job. If you've already got an air compressor, you can have a go yourself with a sprayer attachment that has a hopper.

But whatever you do, match the texture or lack thereof to any drywall that abuts the paneled wall. Nothing screams "I used to be wood paneling!!!!!" like strange, awkward texture on a few walls that, upon further investigation, have more give to them when pushed on.

This is the approach I took on my wood paneled walls and today you'd never know the difference.

The normal way to do this is to install blocking between the rafters (for the ceiling drywall backer) and between the studs (for the wall backer). You don't need to toenail all of them... you can screw about half of them.

Easier from a building perspective, run full length 2x4s (or equivalent) top, middle and bottom of the wall (assuming it's under 4' -- if it's taller, then 2 middles). Run 2x4s on the underside of the rafters on 16" centers. You've probably figured out by now that this is a ton of lumber with the added non-benefit of less habitable space.

Neither of these options require bevel-ing. A tiny gap at the edge of the drywall doesn't matter.

If the underlying problem is the cutting, rent a miter saw for half a day and cut your blocking in one swoop.