with walls , if you laminate you do have the difference in height to contend with. In mine I took out the plaster and put insulation and drywall to achieve the same height because that would bug me. on ceilings thare was no issue. I had a non original crown molding but I chucked it.
You could consider a tin ceiling and avoid the pain? i like the idea of painting them and then putting them up. I like doing it myself, I find it quite therapeutic but the trick is to separate your living space so you aren't living in the drywall dust, just working in it. a plastic divider might be enough to give that separation of work and living space.
probably part of it is that it is hard to hold your hands above your heart for extended periods, so you have to stop and do a jiggle dance as you go ..
you'll build strength in a week or so doing it an hour or two a day. Just dont push yourself.
pole sanding can be awkward too. I find it often easier to get myself right up near the ceiling and sand in circles using a foam pad thing. I sense the hollows as much by feel as by sight. that way I turn my eyes away from the work a lot. I only sand once per coat and I don't use sandpaper to level it, only to knock the bumps and pips off. with wood sand with the grain drywall doesn't have grain and you don't want to see sanding lines , I was taught that if you go in circles the sanding marks dissapear. i sort of sand with the block above my right shoulder and maybe switch hands now and then.
I have the lock feature on my cell phone that reads a fingerprint. I found it impossible to use it because I removed my fingerprints !
so during the job I had to punch in the unlock code. gloves just give me sweaty hands.
the first coats you apply more, and hold the knife more flat to the surface, later when you are just filling hollows you can hold the knife more perpendicular so the knife is sort of scraping it on rather than laying it on if that makes any sense. filling little holes and bubbles is really easy. the finer the finish the more wet you can make the mud since you are putting it on a bit differently. the finer finishing mud is better for that.
I like to do rows as ling as my reach and move sideways , then turn and do the same at 90 degrees.. so mostly I do pull strokes. you might find that some pros throw it on doing more of a semi random arc pattern, whatever works I guess.
if you put too much water in your mud you have to add more drywall compound so try not to add too much. You can't take the water back out easily. I often dip my knife in a bucket as I go to add water to the mix. you'll find the consistency you like by experimenting.
watching lots of videos will help. this one shows how to mix your mud with plaster for filling deeper holes, so they dry fast without a lot of shrinkage. yoiu can put that stuff on thick and it will still harden up. sometimes I mix in glue like if I think it could break from being bumped.
I bed the tape and corner bead with a bit of glue in the mud..it really makes it hard and stable similar to plaster. a gallon of carpenters glue is only about 15 bucks or so and that goes a long way so it isn't expensive. I tried an experiment where i had an electrical box hole in an interior wall that I was covering with the baseboard anyway and just crumpled up some paper filled the hole with plaster, It hardened up and worked well , in that case I was just filling a void that was not going to ever be seen but it demonstrated to me that I can put plaster super thick if it were drywall mud it would not work as it would be way too much in one spot to ever dry right..
https://www.youtube.com/watch?v=sp-RatKtLYUyou can also scrape with a knife a bit.
I'd find a straightedge and check visually first, see how flat it really is before you start. you can hide lots with dull paint and maybe you dont want it flat.. in my place the walls were all pretty well dead flat as plaster so it didn't make much visual difference but some have different plaster. If the keys are breaking you need to stabilize it. laminating over top is easiest because then that holds the plaster issues in place, but you can do it with plaster washers, epoxy etc. i f the surface has big waves that run for feet that is a bit harder to fix but its just about perseverance to achieve the finish level you want to achieve. they make really wide blades. I bought one but just found it awkward to handle myself.
I used Kilz or something similar on top of my plaster after I removed any wallpaper and hot mopped for hours to get the calcimine off, but I didn't skim coat with plaster , I used mud.
if you try and dont reach the level you want then you can always paint and it can always be done again later. the layer of paint won't stop more work in the future. It's nice if you can clear the room of any obstacles. hiring a pro might help especially if they dont mind teaching you and letting you do some of it. Those guys can do in a day what a homeowner does in a week. some like the platter some use a tray. I like the cheap plastic trays because I can put it down and it doesn't run all over if it is thin. a lot of the pros use the platter thing.. your preference.
I dont think the argument about weather plaster is better or drywall is healthy we all respect the originality and realize that your methods should be your choice and you can find the ways you like and your investment , your choice. If you want to restore it like a museum and use only traditional tools and materials, most of us admire that.