A Die Chip Minor Error. Don't hurry it up to a Third Party Grader such as NGC because they won't attribute that type of error
Technically, yes, but one that essentially carries no added premium. As for what it's called, you almost got it... "filled date" is sometimes used, but is a simple and quite common chip/break.
I don't know. Part of it looks like crud. Have you tried removing it with a toothpick? The top part of the loop looks like it might just be damaged. Chris
Looks like both, a chip AND crud. The other kind of neat thing is it's a large date D, the less common variety. I'm betting that live the coin looks less blue, and the wood looks more yellow.
