"head on back" and "the village crazy lady"

Transcript:
Moana: It's time to put my stone on the mountain.
Tala: Okay! Well, then head on back! Put that stone up there.
Moana: Why aren't you trying to talk me out of it?
Tala: You said that's what you wanted.
Moana: It is.
Tala: When I die, I'm going to come back as one of these. Or I chose the wrong tattoo.
Moana: Why are you acting weird?
Tala: I'm the village crazy lady. That's my job.

I've got two questions.
First, what exactly does "head on back" in context mean?
Second, I'm curious about the word order "the village crazy lady". Usually, in a noun phrase, you'd have an order of "adjective + noun + noun" when the noun phrase has two nouns and a single adjective. So, how come it's not "the crazy village lady" but "the village crazy lady"?