There is no best outcome. If you want to be the good dragon don't kill, rape, rob, or eat people. If you want to be the bad dragon do all that. The best outcome is whatever you think it is
It is possible to acquire all captives in one playthrough! But because this is a choice-based game, you can't see every scene in one go. There's a walkthrough linked in the main menu of the game, and another one on Steam.