Should've said - the plaster is past the point of repair, I realize that.

Must I stop all other work in the room, and remove all remaining plaster - to have done it right, & good enough? I HATE the thought of covering (hiding) this, not getting-to-it, & next owner thinking we were sneaky. But... It's all SO MUCH, my dishwasher is done with me - it's pretty much spitting on my dishes & rolling it's eyes at me. Can't replace it because of bathroom repair, already... & school curriculum, more $$ than you'd think, had to take priority - no choice, there.

I want to do this in a responsible way - but maybe not more than necessary, for now?

KS, looks like a LOT of ductwork--it could be moved into the space above the ceiling--later; as for the electrical, looks okay just don't overload the circuits and it will be fine. It's contained in proper boxes and looks in pretty good shape--and it's not k&t. Since it controls switches, cover it up again as long as you don't disturb it you're okay.

Rather than a terrible looking 'acoustic dropped ceiling', what about framing just under the ducts and doing drywall? It will look a heck of a lot better than the grid stuff.

CG, that silly ductwork fills the entire space between old plaster ceiling & gridwork of tacky ceiling panels. Comes in 4' or so, then angles off across center of room to supply heat/AC to vent - right at top of window! (Seems like moisture begging to happen, to me... But I'm wanting it moved to sides & corner of room anyway, so I'm "biased" twice tonight).

I think I should take the plaster away... Shift the duct pipes (w/professionals involved), then (have DH help) apply drywall. I don't want to worry that the next owners will find what I found - & be in a pinch to fix it.

"Should've said - the plaster is past the point of repair, I realize that."

The ceiling plaster does not look all that bad.

The clearly missing plaster is simply gone, and while you could replace it gets very expensive very quickly.

If you can even find anyone that knows how to do the work.

I have to say that you have quite a melange on your hands. The black switch box looks like knob & tube to me, they are carrying a hot conductor through the switch box, and the third lead is the switched hot to the fixture. K&T is infamous for weird setups like that. A real mess. The duct is heat? of fan?
There is a lamp cord plugged into an outlet box in the ceiling. That's really a fire hazard. The black ABS is a drain from above or a vent? if vent it can be redirected no problem, if a drain a bit more delicacy must attend its relocation.
It will be easier/less expensive if you just pull down the entire ceiling and let the tradesmen work unencumbered.
Casey

I have to admit I've covered up a lot worse messes with new framing, drywall and tiles. But only after all plumbing and electrical issues have been addressed.

AS mentioned above, that's definitely k&t. In the third photo from the top you can see one tube. K&T is not inherently unsafe; nevertheless many (in some jurisdictions, all) insurers will not cover your property unless all or most of the K&T is replaced.

Oh, &@#%... now y'all had me up on a tall barstool, poking my phone in for a pic of what I couldn't see. Great.

This appears to be more recent - the flopper, & now owns a "luxury home building company", locally - I just found out. 1st pic, connection seems to be plastic or polymer of a sort?

This is what that wiring is connected to on other side of beam - & HOW it's secured. Guess it's called "electrical tape" for .... This reason?

IF the 1st pic is modern, & 2nd pic (they are connected to each other) is K&T, isn't that just wrong??? I thought one or the other was ok - but not both working TOGETHER... (or is electrical-tape more "magical" than I thought?)!

Perhaps I remember incorrectly. I'm worried, now... We all sleep upstairs, above this, for all these years? (More recent part seems to be a plastic - the last pic piece seems to be ceramic/porcelain, etc).

If the K&T was intact, you could just leave it alone. Once someone starts monkeying with it, all bets are off.

BTW - the first pick in the post above isn't a "connection". They used those ceramic-y inserts to go through joists. They are hollow and the wire should just continue straight through them. If I had to guess, the electrical tape is covering some frayed insulation on the sharp turn.

You will always see a lot of cloth (friction)tape on the K&T joints, which are soldered (so-called Western Union) joints, where the branching wire was wrapped around the main wire and well-soldered to it and then wrapped with a couple feet of tape. The brighter black tape is modern vinyl electrical tape. Since the pic is incomplete we don't know why the new tape was added.
The insulators with K&T are porcelain. The tube ones that fit into holes are always unglazed; the knob ones that are nailed or screwed into framing can be either glazed or not. When nailed, there was a leather washer used to cushion the nail. Very steampunk! Keep it! (after disconnecting it and running new adequate wiring.) You cannot insulate up to or around K&T; it needs to be able to dissipate heat into air.
Oh, the wire itself has cloth insulation, but a stiff jacket insulation, also a black cloth, but coated with some kind of shiny mineral/asphalt compound is used on vertical-inside wall runs, as seen in the pic with the black switch box. It makes the single conductors look almost as large as a two-wire cable, so it's deceptive unless you have seen it before. As seen in the pic, the sleeve insulation always stops outside the box, just where you can see the inner wire's single-conductor status.
Casey

"IF the 1st pic is modern, & 2nd pic (they are connected to each other) is K&T, isn't that just wrong???"

The first picture is a tube, used to pass the wire through a wood member.

The second picture is a knob, used to hold the wire above a surface (side of a joist or stud typically).

They are what make Knob & Tube.

The modern tape indicates someone has messed around with it.

It might be just fine if it is covering old tape or insulation that had fallen off.

There is no requirement to remove old wiring when decommissioning it, and you do not have to install new wiring using the same route.

I would not worry about the K & T if it is functioning. It is quite safe if left undisturbed (think of how many years its been there with no problem!). The plastic electrical tape was probably added because some of the old cloth insulation was missing or damaged during construction of the new ceiling.

You can focus on rerouting the ductwork, etc. above your ceiling. But one other issue might be that you have to remove and replace the insulation.

First, to answer a few questions..

Sombreuil, the large duct/pipe is the HVAC(?), central heat & AC (heatpump). I don't understand why it is this way, perhaps it can be explained simply enough, that I'll understand...

It comes into the room, continues about about 3', (I said "4", previously, but definitely closer to 3), then angles over to the ceiling vent by the window. Couldn't a vent be placed at the wall, right where it comes into the room? It supplies nothing but that one air-vent..

The small black pipe seems to be venting, presumably sewer.

Oh - the lamp cord is the plug-in for that flourescent light fixture flopper put in. (HATE it!). Did he screw that up, too?

There seem to be varying opinions on the wiring... I'm not sure what to think, at this point. Above most of this room is a void, pseudo-attic space behind 5'(ish) kneewall. I can access it - but it's not easy. The insulation, I want to get rid of anyway - it's gross. I could definitely stay away from any electrical when replacing it. (It was resting on/smooshed upon that K&T, I've pushed it up & away for now - what I could reach, at least).

Money is more tight than usual, right now - due, only in part, to this bathroom/laundry room fiasco. (I thought things happened "in three's"? We passed "3", got to "6", still going, lol!). So, the very THOUGHT of bringing in "Mr. Electrician" makes me start to sweat & tremble... I am Chicken Little, by nature.