All very important thoughts and questions.
I would throw in "what is friendship and loyalty" as well. The movies captured those two themes/questions and did a good job. Gandalf basically giving his life to save the rest in the mines, the trio setting out to rescue Merry and Pippin, without really giving a thought to the fact that they would be vastly outnumbered and might even die. Sam staying loyal to Frodo even when he sees the ring turning Frodo into a monster (at the risk of his own life). I won't get into the RotK for those who haven't read it.
I would say the LotR trilogy would be the ultimate "buddy" movie. There are a lot of movies that revolve around friendships/companions and loyalty, but none can come close to LotR.
Gee, did you really think Frodo turns into a monster? He's a little short-tempered with suffering, certainly, but he's really metamorphosing into a type of Christ (as many of the characters in the story do, sacrificing in one way or another for the greater good).