Think we're pretty much on the same page but still some points since it's interesting to talk about

:
- not absolutely sure about David needing a master. I'd argue it's still left ambigious, which is a good thing imo. He appeared in the last third highly autonomous and at one point I was convinced he at least played with the idea of flying away on his own (=freeing himself). That changed of course when he got decaptivated and couldn't move one bit on his own

it was then when he 'surrendered' to Dr Shaw.
- agreed about your last point. I think the movie would have been better if they either explained Dr Shaw's believe/faith better, not just this cliché'd: because my father...when I was young...now my whole life I'm in pursuit of..." kind of thing. That annoyed me in Interstellar just the same. I'd personally would perfer the 'I'm doing it because I'm very curious' (hence got a scientist..). Although that's part of David's character somehow..so at least make these 'believers' a bit more believable. Otherwise they just appear as Dr.Shallow.
Going to see Hobbit III this weekend.