That's an interesting point! The fact that our current theories suggest that no information can ever leave a black hole entails a paradox which is known as the "Black hole information paradox" (https://en.wikipedia.org/wiki/Black_hole_information_paradox). In the movie they resolve this by resorting to gravitational waves, which can "permeate" through space and time by a mechanism not explained in the film. In real physics, there is actually an ongoing debate in the community about whether information can escape from black holes or not, which resulted in a famous bet between Stephen Hawking and Kip Thorne on one side and John Preskill on the other. The fact that Thorne suggests that information can be sent out from a black hole might therefore be a small stab at John Preskill ;)
Concerning the second point, there is actually a pretty fascinating explanation: For a small black hole, the "tidal force" when entering the black hole (i.e. the force difference between your feet and your head) would be so enormous that you'd probably get ripped apart (so-called "Spaghettification" - https://en.wikipedia.org/wiki/Spaghettification). However, the Schwarzschild radius (or event horizon) increases linearly with the mass of a black hole, whereas the gravitational force declines with the square of the radius. Hence, for a supermassive black hole with 10 million solar masses, the tidal force is not bigger than the one you experience here on Earth (https://en.wikipedia.org/wiki/Supermassive_black_hole), and you would probably not even notice when you cross the event horizon. Fascinating stuff.
They glossed over the tidal force in the movie and I assumed it was a deus ex of sorts (in fact, I assumed the whole final act of the movie was more concerned with resolution of the story than with proper Physics). Thank you for this explanation, this is fascinating stuff.
It's still a gloss over, but one of the characters does mention it early on, which I took as indication that it was going to end up being important.
I remember having a similar thought process to all of the above, but they even explicitly call it out as "gentle" with maybe a single really simple sentence on why it was. I don't remember if they made the direct connection to it being supermassive (like they did with its rotation), but it was in the same bit of dialog.
Maybe black holes are nature's true-random-number-generator (via hawking radiation). Energy comes in, energy eventually comes out, but there's no relation as far as wavelength, direction etc.
No idea, I'm an EE not an astronomer, just guessing out of my back end.
Concerning the second point, there is actually a pretty fascinating explanation: For a small black hole, the "tidal force" when entering the black hole (i.e. the force difference between your feet and your head) would be so enormous that you'd probably get ripped apart (so-called "Spaghettification" - https://en.wikipedia.org/wiki/Spaghettification). However, the Schwarzschild radius (or event horizon) increases linearly with the mass of a black hole, whereas the gravitational force declines with the square of the radius. Hence, for a supermassive black hole with 10 million solar masses, the tidal force is not bigger than the one you experience here on Earth (https://en.wikipedia.org/wiki/Supermassive_black_hole), and you would probably not even notice when you cross the event horizon. Fascinating stuff.