1) Abilities' Interactions Within the Moveset and Outside of it

Alpha Strike is one of the most complicated moves in the game, that has a huge list of quirks to it that make it one of the most interesting abilities to master. Here is a list of what it does -

a) It is a Delayed Targetted Blink to an enemy. This makes it a good gap closer.
b) As a Blink, it allows you to reposition in fights.
c) When used, it blinks to the enemy target. However, if the target dies before Yi has lept to it, then after Alpha Strike Yi returns to the position he started from (rather than at the place where the dead enemy was). This allows Yi to farm creeps or even in select situations, steal jungle creeps while returning to a position of safety, by timing the Alpha Strike well. The cost is that one o the 4 Minions will definitely not be farmed since it had to die before Yi got to it but still counts for one of the 4 bounces.
d) It farms and picks up in farming power with levels put in it. It is one of the reasons why Yi is capable of jungling, it acts as an AoE smite. The reason it isn't broken at it is because it has random procs, meaning that his AVERAGE clear speed is determined by the level of Alpha Strike and is not as high early on as you would think. The ramping up factor is important though, it is why he can jungle faster with levels and explore more options, to be detailed later.
e) Yi loses his selection box and hitbox while leaping. This means that moves with a clear hitbox, like a skillshot, won't affect him. It also dodges a move with proper active frames like Pantheon's stun, Amumu's Ultimate, Olaf's Reckless Swing and so on. This is because there is no hitbox for the attacker to connect with so the ability just doesn't apply. It might also pop Targetted Projectiles but this I cannot personally confirm because of all the applications, that has been the hardest to perform consistently. This attribute is balanced by the fact that Alpha Strike commits Yi to a fight and put him right next to enemies, so dodging Amumu's Ultimate doesn't mean you get away, quite the opposite.
f) Because Yi doesn't have a selection box, things that selected Yi before he leaps lose their targetting on him (because he's not even on the map, you can check the mini-map for it). This makes Yi incredibly potent at things like tower diving because with coordination from a team, Yi becomes the only champion currently who can juggle tower aggro the way it used to be able to, allowing him to grab aggro kill someone and then reset the tower aggro on nearby minions so that it doesn't kill him. The risk lies in that this requires alot of coordination, your opponent will typically need to die for sure (so those flashes will make you cry) and there must be something nearby to target with Alpha Strike. But it's a tool in his arsenal.

Meditate is a simple Channeled Heal that also makes Yi tanky.

a) Allows him to continue laning. This comes at the cost of not having a stronger Alpha or Wuju.
b) Allows him to continue jungling. This comes at the cost of not having a stronger Alpha or Wuju, thereby making his jungle slower in comparison to if he didn't need to use it. But it's good if you do need it.
c) Allows him to tank Burst that doesn't involve a silence, stun, taunt or fear. It's not so great of tanking lots of attacks because since it's a channel, it needs you to stand and not fight, taking free hits which either makes your healing worthless or at best a stop gap measure.

Wuju Style

a) One of the reasons Yi has an itemisation mini-game (explained later).
b) Along with Double Strike, allows him to jungle in a way that doesn't require Alpha Strike.
c) Is pure physical damage. Which is a blessing and a curse. It uses lifesteal and crits, which are both good. But is also affected by more mitigation due to being countered by armour. The fact that its activation is timed also means that if you're up against someone with mitigation, if the fight takes too long, you will often wind up weaker.
d) Triple Stacks. Meaning, if you have the active up and kill someone with Highlander active, the skill resets, so you get both the active and passive at the same time. This is one of the reasons Yi can snowball so well within the same fight, he actively gets stronger for killing someone.

Highlander. A strong ability with lots of utility.

a) Resets all of his cds. Re-read these four abilities so far with the knowledge that you could use any of them repeatedly AS LONG AS SOMETHING dies.
b) Increases +as dramatically. Contributes to the Itemisation mini-game.
c) Increases +ms dramatically and gives an Immunity to Slows, which combined with the +ms gives you the ability to kite alot of champions with less mobility or simply escape alot of dangerous situations.

Double Strike

a) Timing Double Strike procs, especially with Wuju helps you push towers down faster than alot others and to jungle as well. There is alot of power in activating Wuju just as you're about to use Double Strike, use it and then have Double Strike come up a second time without Wuju wearing off. The timing can help in alot of situations.
b) Acts as a confirmed crit, since it deals 200% damage every 7th hit, except if you actually crit first, in which case it does 300%. Thus, contributes to the Itemisation mini-game.

I am not very good at making builds but I have found this build for Yi to be very beneficial. Having the doran's ring early game gives you a much better early game. You may prefer to go with Magic pen boots but the berserker's greaves help a lot with his passive. Also taking a lich bane may be a good choice instead of Tri force. Heck I am not amazing at this game so build whatever the hell you want because there are plenty of better ways to build him.