Legitimate questions I have after watching the end of The OA

Really, if you know the answers, tell me. Warning: SPOILERS AHEAD
  1. 1.
    Why was that counselor dude in OA's house?
    I'm legit super suspicious about him 🤔 Maybe he planted those books??
  2. 2.
    What did Steve's parents think when he showed up back at home?
    Wouldn't they just call up that school and get them in huge trouble? Like what?
  3. 3.
    Was OA lying about everything?
    It was SO far fetched, but you just wanna believe ya know?
  4. 4.
    Why did that one dude see Homer in the mirror?
  5. 5.
    Why would Hap even want to go to another dimension?
    Wouldn't he want to stay here and publish his research and crap?