If that's the boat I think it is, your ballast is encapsulated in the fiberglass keel. What looks like keel bolts may have been used to lower the ballast into the hull. Any chance you've gotten water between the ballast and the fiberglass which has frozen and caused a problem?
I think the first step would be to drain out any water that's in there (drill a temporary drain hole), and then to seal to top of the ballast with a layer of glass/epoxy to the hull. Then you can address the surface cracks and fairing of the outside of the keel. I wouldn't worry too much about a slight change in keel shape affecting your sailing performance.