Evenin' All,
indeed Pitchwife, agree that Thorin ranked as high as any Dwarf, and considerably outranked Gimli, who ranked pretty high himself.
I'm not sure I'm convincing myself of this point, but I think there may be a difference between a hero from a settled culture, who is in charge of, say, a unit of soldiers, like Eomer or Faramir, and Thorin's situation, sure he was a Noble, but a noble in exile, living on his wits and without any large force to command. In the first situation, the expectation put upon the leader is one of heroicness, in the second, the leader is only head of a small group of companions, and I think that may be rather different.
I agree that its difficult to square Thorin's orginal gung-ho attitude with the Dwarves' general hanging-back, standing on one leg and looking uncomfortable when Bilbo was about to explore the secret passage. This is however Bilbo's point of view, perhaps the Dwarves thought that Bilbo thought that they would cut him out of the treasure if he did not burgle it personally? They were sticklers for contracts after all. Or more sensibly, that they would likely make more noise than a Hobbit and bring disaster on the whole enterprise. Perhaps some noxious emanation of Smaug was making everyone extra-fractious and selfish at this stage?
Alfirin I'm almost sure I did mean Conan, typo or Freudian slip? nicely spotted!