No. The passport is all you need.
She should not even need a visa, as your wife, if you are a citizen of England.
No. You need to begin the process of naturalization to become a Mexican citizen.
The related link below will provide you with the answer to this question.
Of course; all you need is a valid passport. No visas are required unless you connect flights in the United States.
Yes, you need a Mexican passport to travel to Mexico if you are not a Mexican citizen.
Yes
Of course not, because Cozumel is part of the Mexican Land.
A passport and a visa.
Nothing, just your passport. Some other forms will be issued on the plane.
Yes, you do.
Yes
no