Don't comment on what you obviously don't know anything about. I work in film and have worked as an AC for many years (amongst other positions).
REAL ACs don't use monitors. You can't if you want to pull focus in time. REAL ACs use SCIENCE, they know the depth of field of their lenses and test them extensively before checking out camera equipment. Then when pulling focus they look at the scene and directly at the lens markings. Using their peripheries they gauge the distance of the subject and pull according to the markings on the lens to achieve good focus in time and seamlessly.
Monitors are only for directors and producers to see playback at video village. Any monitor on a celluloid camera is merely there for quality control purposes. They aren't used when the crew is in a take.
The black hole and the tesseract ACTUALLY happened. If they didn't humanity couldn't be saved. That's the short explanation. I'm happy to give you the long explanation should you request or push me to do so.
*2 possibly 3 reasons...
Cooper DOES NOT die at the end. He can't If he does there would be a time paradox. He has to live on for 2 reasons - possible 2.
1) If Cooper and TARs DON'T get out of the tesseract alive there will be no one to tell the survivors of earth about the experience in the tesseract. If that doesn't happen the "BULK BEINGs" (5th Dimensional Future Humans) won't know they have to build the tesseract and who to target the tesseract on (Murphy).
2) Cooper has to also survive to steel the ship and meet Brand. He has to help her set up camp for the surviving Humans on the Ark when they arrive. If he doesn't help her she could go insane like Mann did and this could jeopardize human evolution to the point humans never evolve to become the BULK BEINGs and build the tesseract for Cooper to enter and eject from.
A 3rd possible reason (and this is more personal conjecture - not necessarily explicitly laid out in the film): Cooper leaving is both symbolic of humanity's driving force to keep exploring but in the literal plot could serve to ensure Cooper as a "legend" so (if he hasn't already told humans on the Ark) when he does tell of the tesseract that knowledge will be taken more seriously by future generations as he will likely be seen as a pioneer or a legendary figure.
Such an incredible film and there really aren't any plot holes if you watch it carefully find all the breadcrumbs left by the filmmakers.