1) What is setting to you?
Setting is scenery. What is going on around your character at any given time.
2) What is enough setting, as opposed to too much?
A basic setting should include any distinguishing feature that is important to the landscape, whether it is a certain type of tree, a stange looking person, a mysterious building, a strangly shaped rock, or even a beautiful lake, as long as it can help place your character that is all that matters.
3) How do you apply setting in your own work?
I have trouble with this sometimes, I tend to want to get right to the action and skimp out on the setting, I build the setting as my character interacts with it. but since my character doesn't tend to interact wit scenery I don't usually have a setting. which I always get doct of.