1.I would say the counter curse for the Cruciacus curse(I forget how to spell it so don't judge) and if that didn't work I would try to kill Voldemort and then hide my parents and get them to snap out of it.
2. It would apear to me as nothing. Just air, everything blank,frozen like a glitch on a computer, me all alone nothing to do.
3. I would see everyone happy and mainly because I helped defeat voldemart by sneaking in, going through all of the tortures obstixles to get in so I can save the wizarding world!
4. I would tell her it was OK and ask what was wrong then walk her to her common room.