Is there such a thing?

I have several questions about the multiplayer ranking system that I am not finding answers for.  If no such thread exists, I will try to compile questions and answers here so that people can fully understand the multiplayer ranking system.

For example...

Does leaving a game early count as a loss?

Does leaving the game early cause an increased penalty in the ranking system, as opposed to playing out a full losing game?

Does the ranking system take into account the ranks of the players you are playing with and against?

Does the ranking system take into account the number of AI in the game?

Does having your opponent leave early count as a win for you if you finish the game and beat the AI?

What are the criteria for earning experience to move up the ranking system?

If anyone knows the answers, has personal experience to relate, or can shed any light on the subjects please post.

In addition, if anyone else has questions (regarding multiplayer or the ranking system), please post them and I will add them to the list so they can hopefully be answered.