NFL

1. The other levels could mirror the NFL, too. If anything, the NFL might be a better place to level-set, since the players have a voice, even if the NFLPA is kind off weak sauce. In general, though, I kind of like that the rules themselves can vary between levels of competition. Makes things interesting, and particularly at the high school level allows for things to be adjusted based on varying talent and experience levels.

2. Sorry. That ship sailed decades ago. Gridiron football is the EU Administrative Law of sports rulebooks.

3. This worked pretty well in the XFL. It ends up looking kinda like a punt return, except the gunners don't leave immediately. Fewer players with a full head of steam is a bit safer.

Honestly though, I think we're on a slow trend of slowly removing kicking from the game altogether. Punters have roughly the range of quarterbacks and could be replaced with a kind of hybrid fourth down where incompletions are turned over where the ball lands; kickoffs are already fading into the west like Elves; and placekicking is so far removed from the normal football skillsets that it's effectively just a way to randomize the reward of points for partially successful play in the other phases. Do some offseason alt-league experimenting, and I bet you could replace the goalposts with some sort of throwing target and get roughly the same scoring.