Your English be praised! I was dreading having to correct your massive post, but I didn't have to. I am, therefore, very sorry to nitpick about your spacing: no spaces between the end of a sentence and the question (or exclamation) mark, and no spaces between the end of a phrase and a bracket. Other than that, your English is perfect.
About your questions:
10 & 11) Whilst your connotations aren't wrong, I would be wary of taking this dichotomy as a hard and fast rule all the time.
15) I would be more likely to say that the cat was sleeping on the (arm)chair, but in is permissible too.
Apart from those, I can find no fault with your sentences or the connotations you have attached to them. Very well done on your English again.
[Not a teacher]
Student or Learner