It depends on your local area (check with your building inspector) however, as a rule of thumb:
Space screws a maximum 12" apart for ceilings and 16" apart on walls.
12 inch spacing around the edge. 16 inch spacing in centre of sheet.
Put them in far enough to where you can smoothly run your hand across it but not deep enough to where you rip the paper on the drywall.
the drywall screw didnt come loose the paper that the screw is holding to the wall is what came loose. a screws function is mostly in the head or flange of it. if the head goes throught the paper rather than just indenting the paper, then it ceases to hold anything and the drywall will go in and out around the screw heance the term " screw pop" .
If the drywall is directly onto the concrete, drill into the concrete and use a shield and screw or there is a concrete screw called Tapcon that screws directly into the concrete without a shield and holds much better. If the drywall is on furring strips, either mount the banister on the strips or go through the strips into the concrete.
There are the drywall screw anchors that just look like a giant screw, they just screw in with a Philips and then the correct size screw fits into the same place as the screw driver. Blue (and other colours) plastic anchors you punch a hole in the drywall then push in the plastic insert until the little flange touches, then the screw goes into the center hole to expand for grip in the wall (these are good for low strength hold in other materials) Finally there are toggle bolts, they go through a pre drilled hole and the little wings pop out and the screw gets tightened until the wings clamp down from the far side of the drywall. All use a screw to either hold things up or clamp a hook or similar to the wall.
Paper drywall tape is the same both sides.
No, the prime coat can go on anytime.
Go to the hosptial.
When a large section of your ceiling's drywall is saggy, you need more than a spot repair. Sometimes the problem is so severe that removing an entire 4 X 8-foot drywall panel is the best solution. A few professional hints can make the job of drywall patch repair go more smoothly. Attic insulation should be cleared out Dispose of the old drywall Affix the nails with nail strips Drywall Panels Need to be Screwed In It's time to tape and mud
If the wall is made of drywall/sheetrock/gypsum wallboard, use one or more screw anchors. This is a plastic cone that comes with a screw. You drill a hole, push in the plastic cone, and use a screw driver to thread the screw into the anchor. Typically the instructions are on the package of screw anchors. Larger anchors will hold more weight, but the size of screw anchor you can use is limited by the thickness of the drywall, so the thickness of the drywall limits the weight it will support. It might be possible to use multiple anchors, but that might require some calculation and planning. If the wall is not drywall but plaster and lathe, you can use a lag bolt. This is a long threaded rod with a spring-loaded folding wing-like thing that threads on the end. To use it you drill a hole large enough to accommodate the folded wing. Push it through the hole, and the wings expand and grip the inside of the wall. Turn the screw to pull it up tight. For a brick or stone wall, there are special masonry drill bits to drill a hole, and anchors of plastic or metal that go in the hole. These expand to grip the wall when a matching screw is driven in. If the wall is not too thick, you could use a lag bolt like above. For a wood wall, simple wood screws should work. For smooth tile or glass, consider any epoxy adhesive.
Paster of paris is a form of drywall, so I'm unclear on your meaning except possibly you have a wall with plaster over lath and want to cover it with drywall. You can find the studs electronically and go ahead and attach drywall to the face of the plaster with extra long screws. - Personally, I would rather repair whatever is wrong with the plaster and lath.
If you want to, you can. Do it if you are in a deep relationship.
out
The poly shield goes directly onto the frame before drywall.