A:Answer16-inches is the maximum width for stud gap. Mine are 17-inches and was just far enough to not mount properly. The people who installed your stuff were correct.
A:AnswerPull the mount out and angle to one side. Their are 2 nuts in the center (see in lded photo). They come from the factory pretty tight. Loosen both (jist a little bit). You should be able to tilt it now.
A:AnswerIt comes with about 3” lag bolts for wood. You need to figure out what you can screw into with 16” center to center and either use the hardware it comes with or buy what will work.