1.- Yes, but you can't do that in the middle of the same match, I mean if you've stopped it and you resume it later, your player should be the same as it was when you stopped it.
2.- I don't really get what you meant, but we use fair mode for tournament matches (we might change that next year, but for now it is fair mode), also Tournament mode doesn't exist anymore, it was replaced with realistic mode some months ago, so you might wanna update your game if you aren't seeing it.
3.- Elite controls are the hardest, then simulation and finally arcade, it means with elite controls, mispositioned hits will be punished more than using simulation controls, and the same between simulation and arcade controls, and some more other things that I can't actually remember
. (they should be in the game's doc)
4.- There is a settings file in your game's folder and also at Tennis Elbow's windows menu folder.