(Yeah, blast from the past.)
Just saw it, and found Interstellar amazing. Compelling plot, great character development, engaging drama, stunning visuals, creative problems and solutions. The answers to all your questions are well answered in the movie, and answering them here would take as long as just watching it.
You could fly a spaceship thru a few key plot holes, but they are very forgivable being such a compelling story.
I waited to see Interstellar until it was on cable tv--sat through the whole movie last night.
(warning, minor spoilers)
Visuals--excellent--especially the planets.
Plot--many big problems, but I was impressed with the betrayal at several points--very human.
The locals ridiculing NASA for faking the moon landing at the beginning were very cool--now there was a school where I would fit in...:-)
There should have been a much more detailed and coherent backstory for "the dying earth". Many other sci-fi writers have made that happen. Nanotechnology run amok is a current meme that works as in Greg Bear's book "Blood Music".
Time travel/loop concepts--the book and TV series "Flash Forward" or the book "The Chronoliths" have set the standard--this movie fell far short imho.
If you going to have a Stargate the ancient aliens is a more coherent meme--the bootstrap approach is just too much woo for my taste. Two stars out of four rating by me.