This past year I replaced the floor in my "73"16' starcraft. Original foam was waterlogged and for how long, who knows??
I had the same corrosion and pitting. I wire wheeled the areas, cleaned with acetone, and then used Gluvit. In areas of heavy pitting, 2 coats.
I did have a couple pin hole leaks where I used an aluminum patch stick that you apply with a torch. Love this stuff, I used it on 24 Crestliner Sabre HT, plugging old transducer screw holes inn the transom with never a problem. As far as the anode thing, If your boat is a trailer queen, or if you don't use shore power, I wouldn't bother. JMHO