Yes. That's pretty much the way it is. They make tunnels about 4 to 6 inches deep. They don't really dig, it's more like they swim through the dirt. They are destructive as hell. They do have a few favorite vigis. I had them move in and eat a large garden, 50' x50' of sweet potatoes in one weekend just before harvest.
They do eat what you said, but they get them from around the roots of plants. There goes the plant. They are very territorial. Maybe less than a half dozen per acre, but then sometimes they are everywhere. The best way to get rid of them is spray with caster oil and water. About 2 tablespoons oil to a gallon of water. It doesn't kill them but after about a week they will leave. That may work on gophers, to.