Sorry, I'm not sure why this didn't get answered right away.
Assuming you're not playing with keyboard and controller at the same time, it's all fine. I don't think it's been discussed before what rules apply when using e.g. controller and keyboard simultaneously, though.

You have to jump at a "seam" in a wall, where two wall tiles meet. Then, there is a chance the game will give you a small window to jump. So if you jump again during this window, you will walljump.

Player level speedruns are something more suited to the category extensions leaderboard.
If you send me a video of your run along with the rules for the category, I can add a new leaderboard there.

The video doesn't need a timer, you just have to calculate the time yourself afterwards.

The game softlocks because you are then unable to activate final level, at least until you start a new game.

Blind Grav is just blind luck (ha) whereas intermission 1 requires you to actually know what you're doing. You can probably optimize your strategy for Gravitron but just by trial and error you will get through it eventually, even if you're blindfolded. Keep in mind also that after a certain number of deaths it does actually get easier, so the more you die the easier it gets (up to a certain point).

You must play on an official release of the game to have a valid run.

Example from The Witness leaderboard:
Run link: https:/​/​www.​speedrun.​com/​thewitness/​run/​yjk9e6gm

Runs done on the same date one year ago (e.g. 02/02/2019 at the time of posting this) are displayed as being done "1 years ago".

as far as i know, BBhab's PB route is the best known route for gravitron skip. HOWEVER, i would strongly recommend you to use the route that mohoc and myself used in our 12:06 runs (you'll have to toggle showing obsolete runs to see them) or follow the route in emmoji's PB. in general, if you aren't sure what to do somewhere, it's often a good idea to see what emmoji does (which may not be the fastest, but it will be very consistent).

here specifically, the checkpoint death + tower first strat saves 1-2s in total, but you will lose a significant portion of your runs to skipping the two really annoying checkpoints on the way to warp zone. in addition, you are forced to start with the easiest level and go almost in descending order of difficulty, which is very suboptimal. it's much much easier to get a good run with the route not using checkpoint shenanigans at the start, even if it's "optimally" slightly slower.

This is a known bug (transition quit glitch), but it's not useful in the speedrunning realm as of yet.

~3 second timesave in ThwompTutorial

Here's my versions of LaserBounceChange
first one is the same speed as current strat
second one skips additional cycles

There's a level editor built in to the PC version (not sure about 3DS), or there's also the free Make & Play Edition which allows you to make and play custom levels, but not the main game.

I don't really see a good reason for that to be a category for a couple of reasons.

1. Is there a publicly available download link? I couldn't find anywhere to download the beta version officially. If there's no way to distribute the game, the leaderboard will be inherently unfair because not everyone can compete.
2. What does it add to the leaderboards that isn't already there? I think it's in a similar position as Player Level speedruns, where it wouldn't be a very popular category, since it's not necessarily the most polished experience you can have with the game. The official release has been patched many times with good reason.
3. Where would you draw the line if someone asked about adding a v1.0 category? A v1.2 category? Adding version exclusive leaderboards is risky, because it unnecessarily divides very similar categories for no reason.

If we were to create a VVVVVV category extensions page, we would certainly consider it IF there were a publicly available download link, but other than that I don't think adding a beta leaderboard is worthwhile.

As a side note: The current Any% WR may only be achievable on v2.0, but you would still be allowed to submit an Any% run on any other version. There is also a publicly available download of v2.0 on Steam.

100% is now a subcategory for both Glitchless and No Death Mode 🙂

A video would help, but I think I understand what you mean. Does this work in time trial mode?

What exactly do you mean by skipping essentially all of SS1? I'm not sure I know exactly what you mean.

There are other glitches not exclusive to iOS that allow you to get more than 20 trinkets 😉
It only makes a difference in the amount of trinkets displayed on the end game screen (and wherever else the trinket count is displayed).

Interesting find nonetheless, as your method is probably significantly faster for 105%.

Text storage only works on v2.0 on PC.