Wholesaling the land on a burned down house

[Victor Oben]

I have a homeowner whose house burned down. It's likely a teardown. He currently has a mortgage in place, and is going to be getting a check from his insurance company. If I wanted to wholesale the land to another investor, how do I determine the value of the land in order to wholesale it? Also what happens to the existing mortgage? Does the insurance company pay off the bank?