You have several choices when repairing a mirror. You can try the Gorilla glue and put it at several places to make it secure. If that does not work you may have to make a new frame to hold it in place.
That depends on the size, thickness, and weight of the mirror.
A small, thin mirror...say 8"x10"...can be hung with one or two drywall screws, but you're best to use the screws with the 'butterfly' screw-holders that flex out into an 'X' when a screw is put through them; It distributes the weight more evenly and over a wider area so it doesn't tear out the drywall.
A larger mirror such as a full-height, one with a heavy wooden frame, or something like a medicine cabinet: I'd suggest at least two wood screws bored into the studs in the wall. Many building codes require a stud every 16", but a little electronic stud finder is the easiest way to be sure; they're not overly expensive, and will help with any and all 'hanging' needs in the future, so aren't a bad investment.
If you're renting, make sure to check with your landlord about the maximum size of any holes in the wall, and also if frequency will be an issue [some landlords don't care about using thumbtacks to hang posters everywhere...others do, for example] before installing the mirror, to ensure the return of your security deposit.
I wouldn't recommend compounds such as 'poster putty' or 'As seen on TV: Hercules Hooks', or anything else that relies on a viscous or chemical bond. The compounds can change over time...weakening the bond until your mirror goes crashing to the ground, hardening until it's impossible to remove without damage to the wall, or even chemically reacting with the wall and leaving a permanent stain.
-A former cabinetmaker
ANS 2 - A small mirror can be stuck to drywall with silicone. -A large one should have 4 corner brackets held with screws. -It's easy to fill screw holes in drywall later if you have to.
Silicon will glue it on, but it's much better to use small 'mirror brackets' that screw in.
Neither use adhesive
Look to see if there is a small set screw on back of the mirror assembly. Loosen screw and the button should slide out. Clean old adhesive off the window and button thoroughly (small flat razon blade works great). Apply the setup adhesive and allow 2 minutes to dry. Then apply liberal drop of adhesive to the button, and place button on the windshield. Allow 15 minutes to set up, and then reapply rear view mirror.
Drywall anchors should be placed no more than 16" apart. On a 20 foot wall you should place approximately 15 drywall anchors.
Plastic sheeting works well for this, and yes it goes behind the drywall on exterior walls to help prevent moisture from getting to the drywall.
Yes, it should
You will be very careful when you deciding for the drywall color. You should not check the color when there is too much light shining on the wall. After that you can find color you want for your drywall repair.
You should never anchor a wall arm like this into just drywall. It is very dangerous. You will need to find a wall stud under the drywall to anchor this into.
One should fasten their seatbelt whenever they enter a vehicle or similar structure that they intend to travel in. This should also be done for short trips- a seatbelt can save a life at unexpected time.
This could be caused by the drywall being damp. But you also shouldn't have any spackling compound there, - it should be drywall mud.
Buckle up. Fasten seatbelts.
There are many types and sizes. Far too many to describe here. You should visit a drywall wholesaler if you are that interested.
securely fasten your PFD!!