Just my opinions and nothing more than that.

Chekhov's gun, I think an object mentioned in passing early in the narrative has to prove to have significance, but that significance need not completely carry the story to it's resolution. It should be important to the conclusion perhaps, otherwise the reader will wonder what was the point of mentioning it.

An epiphany should dispel confusion and in the case you describe, I would say it would perhaps apply if/when the two farmhands realize their mistake and that they've been pranked.

I'm not sure what a Repetitive Designation is, so I can't comment on that.

Allusion is an indirect reference to something, in what you describe I would say the neighbour could be inferring that Cleat would be a better farmer, and basing that on the argument that Farmer Pete went and got his GED to become a better farmer. Since the GED and being a better farmer are both explicitly mentioned, I wouldn't say this was allusion.

I could of course be wrong, but then I get to use the blush emoticon, so that's okay (It moves me forwards in my scheme to use all the face emoticons).

Anyway, hope this is helpful.

On a related note, I worked out how to deliver some poetic justice to one of my characters today.