A head gasket might get your #1 problem solved. Before that I would have the head critically checked by a decent shop for flatness and cracks. Primarily the number one chamber for any evidence of cracks.

Also since there is a slight chance a crack is in the valve feed passage. A head pressure check would be even better. Nothing like spending other peoples money though. The only thing really certain is that coolant was getting in there somehow.

You did not post a head gasket picture of both sides. A close up of the #1 area would be best. It might help if you do and might not.