Fantastic review. If you truly are an astronomer, i love the angle and honestly you bring to the review. This is my favorite movie of all time, I have seen about 10 times. Even though it is not perfect, it is still one of the most realistic science fiction movies out there. Christopher Nolan did a phenomenal job at bringing realism into a place that is covered with theories.
To respond to some of your points. When they came back from Miller's planet the reason why it was 23 years was that Anne Hathaway, Brand, miscalculated the time. It was pushed pretty heavy that it was 7 years but when they came back you can see her being upset with herself saying "I thought I had it right, the numbers were right" something to that extent.
The light I am pretty certain was coming from a nearby star, usually depicted behind or just beyond the horizon of the black hole.
Still this is a great honest review. What do you score this movie out of 10?