you jumped over the hitbox, it's smaller than the visible model
you should find what you're looking for at around the 8 minute mark
why
calling change.org right now, hopefully this one gets to the senate.
It's allowed for single stars, but not for stage RTA. Technically both of those fall under IL's (depending on whether or not you quantify stars or stages as 'levels'). Assuming you are referring to the submissions on this website, (single star records are not stored here on speedrun.com) which are the stage RTA boards, then no you can't use emulators.
It seems a bit too arbitrary to me, but if you ever do a run of it, I would check it out.
It will, he just said you timed it wrong. If you would like to retime your runs yourself the timing method is from the first frame Mario appears to the first frame peach appears. I believe that is also mentioned in game rules. Timers like livesplit are always an approximation because of human error.
That's perfectly fine, although you might find yourself having some trouble with the unnotched analog stick. Pretty sure you can use any controller you want as long as it doesn't have turbo, anyone else is is free to clarify whether or not I'm right about that.