The fantasy fiction formula

There's more to writing a successful fantasy story than building a unique world or inventing new magic. How exactly is a plot put together? How do you know if your idea will support an entire novel? How do you grab reader attention and keep it? How do you create dynamic, multi-dimensional characters? What is viewpoint and do you handle it differently in urban fantasy than in traditional epics? What should you do if you're lost in the middle? How do you make your plot end up where you intend...