User Manual AmazonBasics MP0070-W Projector

Yes, comes with an extension to drop lower if needed or hug the ceiling without. But you need to have the electrical box (as used for any lighting fixture) to mount to.

No. I had to mine is on some L shaped aluminum to make a slide of sorts

I did receive the instructions. It was very easy to put together.

No. The projector is attached using screws. There is a section of the mount itself that comes apart quickly but you'd still have to loosen 2 screws and most of the mount would still be attached to the projector.

How do you mount this to the wall? I just recieved mine and it has no wall mount instructions!

Use stud finder and locate the beam behind the wall. Place the back of the wall mount there and mark the place of the whole on the mount on the wall. Get a drill and drill 2 or 4 holes on the wall where you marked. Make sure to drill the whole only with the thickness of the screw base not the entire thread thickness of the screw. Put the mount back to the wall where the holes are adjusting
the four screwholes of the mount to the holes drilled. Do not worry about angling or adjusting joints of the mount that will come later. Drive in the screws with a screwdriver and a phillips bithead. The mount should sit stable and still against the wall. You need to put on the joints one by one except the one that attaches to the projector. That one you screw on the projector first and once you have done it, fasten it to the blower joint of the mount already on the wall. Hope it helped.

Periodically clean your mount with a dry cloth. Inspect all screws and hardware at regular intervals to ensure that no connections have become loose over time. Re - tighten as needed.  
Users should check and maintain the product frequently to ensure the TV and mount work normally , safely and securely .  Make sure the screws are tightened every two months