Woulda, coulda shoulda

Factual Questions
1

Shoulda Woulda Coulda is a song by someone I’ve never heard of. “Could’a, Would’a, Should’a’” is the name of an episode of Farscape. I think I may have heard an iteration in an episode of NCIS. I’m pretty sure I heard it IRL a long time ago.

What is the origin of the phrase (I’m not looking for the meaning), and what is the ‘correct’ order of the words?

The order as used in the Farscape episode title makes the most sense to me.

2

I always heard it “woulda coulda shoulda.” Dunno the origin, and Google (which I presume you tried) is no help.

3

Line from the song “Test” by Ministry:
could’ve, would’ve, should’ve - it’s too late - WAKE UP!

That’s the order of the words I always think of.