1. Usually a star washer means ground. Though, in that area, there usually isn't a separate ground wire for anything. In '68 there was a ground wire added to the instrument cluster that goes to the pedal support brace. You might have to just try to get in there and look around for a wire hanging or an empty hole. Not easy, I know...
2. Yes, the radio power wire is Yellow. And that looks like the correct type of connector for it, too.
3. Do your headlight doors work? That is the connector for them. Correct colors, too. I believe it is in the correct location, as well.
Yeah, I am not totally sold on the washer being there for a ground so if anyone has any other ideas of what it might be for let me know. It has me stumped, as it seems it was more stuck to something than connected to something. When I pulled out my old dash harness to replace with a new one it just fell out, I just cant figure from where???
As for the headlight doors, is that connection off the dash harness? I have that installed but do not see/remember a connection from the dash harness to that connection near the fuse box. Or is that connected to a different harness (ie rear, engine, ect.) Thanks for the help...