Has anyone won a criminal appeal? If so, how and how long did it take?

Answer 1

90% of appeals that are won are remanded back down to the court where the trial occured and then the same verdict is rendered after another trial. Most of the appeals won are on issues that don't affect the outcome of the trial.

Answer 2

It is rare. But it happens. It usually takes a year or so, and usually the result is a new trial, not dismissal of charges. The time depends greatly on the state involved.