I assume that you alreay have the duct work in place, and the drywall over the duct. The problem is that there is nothing for the register screws to bite into. Instead of using the screws that come with the register, use "sleeve type - hollow wall anchors" (butterfly clips), they will expand into the space, holding the register in place. Hope this helps!
The ceiling grid is not going to help all that much. not on that long a wall. How far above the ceiling is the roof and is there something there that a brace could be attached to? A V brace every so often or do the wall in sections with a longer stud between each section that extended to the roof structure.
It is possible for smoke from a wood heater or fireplace to attach itself to the wall where the studs are located. Somehow the studs act like a magnet, I have had this happen in three homes previously.
To attach crown molding to a ceiling, first measure and cut the molding to fit the length of the wall. Then, apply construction adhesive to the back of the molding and press it against the ceiling. Secure the molding in place with finishing nails or a nail gun. Fill any gaps or nail holes with wood filler, sand the surface smooth, and paint or stain as desired.
To frame a ceiling for drywall installation, first, measure and mark the layout of the ceiling joists on the walls. Then, install the ceiling joists perpendicular to the wall studs, spacing them according to building codes. Next, add blocking between the joists for support. Finally, attach the drywall to the ceiling joists using screws or nails, ensuring a smooth and even finish.
The ceiling.
The ceiling will be very warm, while the floor will be cool.
The line where the ceiling meets the wall is called a cornice. A cornice can be set off from the ceiling with the use of cornice trim. The line where the wall meets the floor is called a baseboard.
A ceiling partition is a track on the ceiling that may have a metal or wooden wall fitting into it. This divides a room by the ceiling support.
Why would you need to? The wall is holding the ceiling up. A better description of what you want to do would help.
This tv can be mounted on the wall only.
One way to construct a partition wall in a room without attaching it to the ceiling is to use floor-to-ceiling support columns or beams to hold the wall in place. These columns or beams can be securely anchored to the floor and provide the necessary support for the wall without needing to be attached to the ceiling.