I just added a FD to my sorcerer, and looking over the skills, it gets all the dragon class skills. to reverse engineer their skill scores, all the ones listed on their page get 3 ranks. As for familiar class skills, I believe it says add them, so they should get both. Though, these would be untrained, so matters very little.
As for HD, yes he gets half the characters hp, and is considered to have the same HD, which my DM ruled means that his spells are considered to be cast by an sorcerer of my characters level. But he does not go up in level (no more spells, etc.). he decided it would help scale him up as we level up, but not overpower him.