JB Weld, screw em in, magnets, even hot glue can work for the ears. Same goes for the visor. However, I just simply duct taped mine in there. After trooping in 4 events, one being a 5k run, I think I can attest to how well tape works.
Painting inside...just be careful. Remember that you will sweat in there, so be prepared for some of it to come off on you. I have not painted inside any of my buckets, but have thought about it.