Can anyone advise the cost of removing such duct (about 2-3 meter long), together with the removal of the hooks to support the duct in the ceiling, as well as to close off the vent at the cut off place?

The attic space is really open and has 8 feet high ceilings (the roof).  

He was in the small crawl space in the ceiling working on the electrical for a light that was flickering and needed to be fixed.

I had them redo the whole ceiling. 

Some of the ceilings are plaster and some have ceiling tiles which creates similar challenges once they are removed and patchwork required.

Some of the ceilings are plaster and some have ceiling tiles which creates similar challenges once they are removed and patchwork required.   

For larger ones like 3 or 4 bedroom single family with tall ceilings I'm curious how the ozone machine does 

The water seeped down and caused some ceiling damage to the unit below mine. 

The issue comes when the smaller, 1990s houses with popcorn ceilings, laminate counters and full carpet see that and think they can as well. 

And again at the risk of sounding naive & being real honest here... we know nothing about building, seemingly, it wouldn't be too ridiculously expensive to build say a rectangular 1500 ft² house on a slab where all you really had was an open kitchen to living room and then on either end of that a master with a bathroom other end 2 bedrooms with a bathroom in between.The main thing which, I know is probably the most cost (and this is going from an amazing airbnb I stayed in with girlfriends called the skyhouse, which I zillowed by the way worth $650000 our budget only about $350 K)We want both sides of the big main room (kitchen & living room) to have  Florida ceiling collapsible windows so that you can have a complete open field in the good weather.A pool would be amazing but can come later.HELP???