In regards to Cooper going out of the Black Hole. He says that "they are doing for me what I was able to do for Murph" or something to that effect. I take that to mean that they allowed him to communicate the data and complete his promise to his daughter, so they place him back in the wormhole so they could do him a favor of letting him see his daughter again.

I think that the tesseract was made by evolved humans that were millions of years in the future that needed to preserve the species by constructing the tesseract and leading Cooper to that spot.

My final opinion is that the equation and data allowed them to manipulate gravity to the point where they could lift the big space station off into space, thus completing Plan A. Hence the smaller shuttle craft at the end which Cooper used to go find Brand. He would need gravity in order to survive or his bones would deterioriate in the time frame it would take to get to Brand's planet.

The great thing about this movie is that I don't know if there's necessarily a right or wrong answer or that there needs to be. The message it portrays is extremely powerful and one that we need to heed or we may just end up ruining our own home.