Correction for the last part: Spamming Z does not boost Rude Buster damage as much as it used to. Starting from Chapter 3 onwards, you must time a single Z/A press to get the maximum damage boost. (Perfect timing would be right as the buster hits the target) This was how it was supposed to work all along but broke in the first 2 chapters. (Still is and it's unlikely going to be fixed)

My approach would be to make 2 subcategories, one for current lowest percent records and one for legacy records. (records that were placed on a previously thought to be lowest percent)

Any way that I can rub the lazer thing faster? (Edit: found an old comment of mine, just remembered how)

I was also thinking of difficulty-specific speedruns like say, 10 normal levels.

That's an interesting idea.