What is leadership?
Can one be gluttonous, cowardly, and self-interested and still be a good or effective leader? Is leadership the same thing as authority? Does leadership rely on - or, indeed, is it synonymous with - good communication?
How you answer those questions is up to you, but I'd answer them like so:
1)Leadership is the ability to guide a group of people toward a goal. Good leaders have the ability to prioritize different goals, to explain their strategies to their followers, and to gain the trust of those followers that they are being co-ordinated in an effective way towards a goal they all share.
2) Yes, you can be a selfish asshole and still be a fantastic leader, provided that there's a sufficiently well-designed metric to tie your well-being directly to the well-being and success of the people you're leading. This is one respect in which I'd say democracy is broken - a politician's primary measure of success and reward is re-election, when it really should be more objectively meritocratic.
3) Leadership is absolutely not the same thing as authority. Authority simply gives you the ability to lead, it is in no way tied to proficiency in doing so. The two frequently are not related.
4) Finally, yes, I would say that effective leadership is, in fact, a form of communication. It isn't prodding people down a path with a sharp stick, it's showing them an open door towards something they already know they want to achieve.
And I'm terrible at it.
Seriously, never do what I say. I'm the worst.