You're welcome!
1. I played in HTML, for me it opens up in a popup window and fullscreen immediately. Using firefox, if that helps.
4. Oof this is hard to remember. I think it was at one of the levels where there was a partial roof made of keyblocks above the target. My shot bounced when I tried to go through sideways. Maybe it was just a wonky collision, and not an intentional invisible wall :D it clearly should've gone through to the target but it bounced off the (in my eyes) invisible wall. But it ruined my oneshot solution :D