Is there anywhere that we could use to quickly learn this game? Any guides, tutorials, etc? I appreciate any and all help

Sorry for late response. I'm not aware of any kind of tutorial but can give basic advice for now: to gain fast momentum as in speedrun you have to first gain speed with holding B for a moment while walking , realese direction button (right or left) then press down, from this point on you will have the fastest speed. You cannot press left or right (or you will immediately lose it ). To keep it, you have to stay in the air jumping asap every time you land or mash down being on the ground, so character will slide and keep it as well.
Sliding underwater works in a little different way: you have to press A then down around 3 frames later. It's very precise, annyoing and if you miss it (which happens to everyone) you won't move at all. You can always try to mash down and A (trying to keep this 3 frame difference between them) and it still should be usually faster than just swiming through the level.

One more thing: don't try to copy route from the best two runs on leaderboards. They utilize much harder and just a little faster Furbal starts in world 3 and 4 plus Buster only wacky land. The best way is to watch garadas' 12:44 former WR, where plucky is used till final world. I don't recommend attempting Furball route untill around low 13 time, when you should already have quite good feeling of the game

One more additional thing: watch your carrots, if you finish world having odd multiple of 11 (11,33,55,77,99) you will get bonus round, which cost around 13 sec if you die there fast.

There was a joka tutorial for big 20 but I can't seem to find it anywhere. FeelsGoneMan.

Also, to do the 1-3 clip, basically you use the down boost to get speed and you want to aim for just below where the stairs meet the brick. As you hit the brick (maybe even a ways before) tap left to face the other direction. you should clip in and be pushed right through the wall