I first heard the word "mensch" when I was starting to learn German as a kid. Never quite heard of the mench iteration of it before, but hey - if it's on urbandictionary then it has to be correct ..... right?
The word "there" can appear as a pronoun, as in “over there".
"Their" is a possessive pronoun. In a phrase like “Susan and Bill's car,” it could be used to to make a new phrase: “their car.”
”They're” is a contraction of “they are.”
“They are” should always be able to replace “they're.”
Extra credit: It's "I'm looking for an M3" not "I'm looking for a M3".