Axe and Laijin have different styles of play, yes, but it takes more than just watching them play to properly learn anything. If you're gonna watch people play, you have to take mindful notes (what YL did, why he did it and the outcome of it---both when he messes up and when he succeeds) and practice the necessary tech. Remember that, especially when playing a lower-tier character, you really have to understand the character in and out. That's different from being able to situationally regurgitate stuff you saw Axe and Laijin do.
I'm going to guess you at least sort of know what the terms you mentioned in the OP mean, especially with something as specific as bomb ledge canceling. In that case, just practice it. Practice everything. Find all sorts of applications for everything. Embrace the cheese.
"Lethality of the boomerang" doesn't really mean much. If you know when to use it, it's great. If you don't know when to use it, it's not quite as great. Boomerang has a decent amount of knockback and can be used to bait people into shielding, dodging or moving to a less advantageous position. It also cancels whatever you're doing if it makes contact with you when coming back to you. You could theoretically use it to instantly cancel dair lag and even use up-b twice (or up-b into hookshot), but that kind of thing is insanely hard, and the boomerang is a little wonky, so it wouldn't be something to rely on.
Crouch cancel moves that aren't dumb to crouch cancel, I guess. Low-damage moves with decent amounts of lag for the attacker are pretty good to crouch cancel. Ganon fair and Peach dsmash are awful to crouch cancel. It's often not a bad idea to crouch cancel Sheik's aerials (especially nair) and d-smash. Crouch canceling space animal moves can be risky because if they l-cancel it correctly that shine can come out really fast.
Combos to dair are matchup specific. Bomb-dair is pretty trusty. It would stand to reason that people know that YL will want to hit with dair, so opponents might be ready for that. Keep your options open.
Moonwalking is mostly a flashy thing imo. Falcons use it to look mad stylish and sometimes land a bair or fair on someone way out away from the ledge. I think it could a mixup at best; honestly I think it mainly just nets style points.
Honestly, the best thing you can do is play the game and see what works best. There's only so much that watching other people and theorycrafting can do. You have Laijin and Rhan in your area. Get in touch with them; they are excellent resources.
But, really, nothing beats just picking up the controller and playing.
main but seeing the potential of 
