Can anyone explain the word order in the case of "gemeinsam" and "mit ihm"
The construct used here is "etwas gemeinsam mit jemandem haben" - "to have sth. in common with someone".
The word order of the object and the "gemeinsam" is not important. Both "... mit ihm gemeinsam" and "... gemeinsam mit ihm" are correct.
"I have nothing common with him" — why is this answer wrong?
Sorry, I'm not native English speaker, maybe it's wrong sentence, and "in common" is the required phrase here?
Yep, that's it.
I can never hear the difference between "Ihm" and "Ihn".
I write one, and inevitably it ends up being the wrong one.
Don't judge by sound, but by context. I can't think of any sentence, where "ihm" and "ihn" would be interchangeable. (There is a recognizable difference in pronunciation though)