Some Opening Questions I Have...

1.) Why is the King's Indian Attack setup different from the King's Indian Defense? I've read King's Indian Attack goes like this:

But the King's Indian Defense games I've seen doesn't have that Nh2 re-route. Why is that? Why does King's Indian Attack put all pieces into one side? Will it be a problem if I play the KIA setup just the same as the King's Indian Defense's f5 pawn break?

2.) I've recently found this opening against the French called the Schlecter. It goes Bd3, with plans to re-route the Bishop to f3, and have the Knight just settle on e2.

Does anyone use this? Funnily enough, I've actually been using this since forever against the Caro-kann; didn't know it was for French. I must say, it's... so-so? It's not that bad, it does stump 99% of Caro players. But it also kinda doesn't do anything. Game just turns into a passive opening for both sides, where neither of us are trying to touch each other... The c6 in the Caro-kann really stunts the f3 Bishop, but maybe it works better in e6 French??

3.) How to play the traditional Scandinavian. Okay, this has been bugging me for a while now... Wikipedia says the pawnbreak in the Scandinavian is for Black to play c5 at some point, maybe even e5. But the games I've seen has Black expanding on the Queenside instead with b5. Which is it?? I'm so confused. Does anyone have a simple system for the Modern Scandi? Because if you do, I'm completely ready to abandon Qxd5, it just feels off for some reason.

I think I've read once that Modern goes like this. Correct me if I'm wrong:

(I can't remember if that White Knight is supposed to get in or not...)

The pawn structure the opponent chooses is different. The most obvious thing being that if white plays e4 and d4 (without c4) then it's a pirc or modern, not a KID.

The other obvious thing is that white can play an early e4 in the KIA, but black can't play an early e5 in a KID

If there's no pawn on e5, then f4 is not a pawn break. A common structure against the KIA is to have pawns on c5, d5, and e6. A common way of attacking with the KIA is piece-centric (i.e. you're more likely to open a line to black's king with a piece sacrifice, not a pawn break).

Yeah, it's fine.

And yeah, the rubenstein-style french (3...dxe) requires precise play by white to get a good, or "fun" position. 3.Bd3 is just equal, so I wouldn't be surprised if the positions get a bit boring.

In 2...Qxd5 lines, yeah, your breaks are typically c5 or e5. I know there are some funny lines where black retreats Qd6 and pushes a6 and b5, but that's mostly for fun in blitz games. In the typical pawn structure black is indeed breaking with e5 or c5 at some point.

If black gets a bad position, and is desperate, then maybe queenside expansion happens, but the most logical and correct way to equalize is getting e5 or c5 at some point.

The 2...Nf6 lines are objectively not very good (unless you're playing an inexperienced player who tries 3.c4, in which case it's just equal).

There are multiple problems with your logic.

1) That is not White's only setup.  In the KIA vs French, yes, that is White's most common setup.  Against the Sicilian, often White plays h3, not h4.

2) The 2 openings are nothing alike because openings are not decided by the moves of 1 player.  They are decided by the moves of both.  For example, just because you play e6 and d5 as Black does not make it a French.  White must play e4 and d4.  If White plays d4 and c4, it's a QGD.  If White plays Nf3 and c4, it's a Reti.

Look at White's position in the KID and Black's in the KIA.

KID - After 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6.  What is White's weakest square on the board?  If you do not know the answer to this, you do not understand the KID (most don't, actually).  It is d4!  With the pawns advanced to c4 and e4, a pawn will never again cover the d4-square.  This is ultimately why Black attacks d4 with 5...O-O and 6...e5 if it does not lose tactically (like in the Averbakh or Four Pawns, where 6...e5 is bad).  Black can follow up with ...Nc6, again hitting d4, forci g a decision from White.  If White closes the center with d5 (the most common), ONLY NOW is the e5-pawn safe, and Black now plays the pawn break f7-f5!  Black should NEVER play this If d4-d5 has not been played!

Now look at the KIA.  It is most often played against the French and e6-Sicilians.  There is no Black pawn on e5.  The d5 pawn is NOT WEAK!  Therefore, White's play in the KIA is not the same as Black's in the KID.  The Black d-pawn is guarded by a pawn, f4 is not a pawn break, the center can still be opened (exd5 or ...dxe4).

Apples to Oranges.  KIA theory and KID theory are like Britney Spears music and Metallica music!