None of the dwarves are really described that much in the books, so the most we get on their appearance is the colour of their beard or their hood (Dori's was purple). Beyond that we know he played a flute, enjoyed food and grumbled a lot, but was generally a 'decent fellow'. His main role in the book was pretty much to carry Bilbo around, he carries him through the Goblin tunnels and Bilbo grabs his legs when the Eagles save the Dwarves from the Wargs. Mark Hadlow plays him fairly close to the books, though his mother-hen tendencies are a film invention.
Dori's not really noble, he's one of Durins's folk, which means his distantly related to Thorin, but not as closely as Balin and Dwalin or Oin and Gloin. So it's more like he's from a respectable, well off family than nobility.
The Lego Hobbit game probably comes closest to the Dori you're imagining, you can play as a young Dori in the first level and buy him later on. He's a pretty hardcore warrior and you use him to help Thorin when Smaug attacks Erebor
