Fianchetto openings

I get everything is judged on a case-by-case basis, but I want to understand which moves are more likely to be the best.

Is kingside fianchetto not as preferred of an opening as e4, d4,and English c4 because it creates luft on the g and not the h square? Why did I read a-pawn luft is good on queenside castling when it takes the king one move to get to the b square?

From what I understand, kingside castling is preferred to get the king away from the attacked center (c pawns are more encouraged to be pushed than f pawns, unless you go f4 or f5). I have to watch some videos to learn more the dangers of queenside (besides understanding the fact that the king is near the center). I queenside castle 90% of the time to get the rook to attack the center in the game, earlier, in quick times when I don't think very well.

So are fianchetto openings just not preferred just because it pushes that g or b pawn?

No, a fianchetto normally strengens the Kings position (as long as the Bishop remains). Other pawn moves in front of the King do makes luft, but also weakens the Kings position - so don't make them to often.

The main reason why Kingside fianchetto is not as popular as eg. e4, d4: The concept of dominating the centre without pawns is more advanced and more difficult than the older concept where you dominate the centre with pawns.

The reason most people prefer Kingside castling is probably that it is quicker to do (you only have to move two pieces). But queenside castling is fine and can often produce interesting games with opposite Kings.

#1

"Is kingside fianchetto not as preferred of an opening as e4, d4,and English c4 because it creates luft on the g and not the h square?"
++ The essence of fianchetto is not to create Luft, but to develop the bishop so that it controls not 1, but 2 central squares.
Bd3 controls e4, Bc4 controls d5, Bb5 indirectly contests influence of Nc6 over e5 and d4, Be2 asserts influence of Nf3 over d4 and e5, but Bg2 controls e4 and d5.

"Why did I read a-pawn luft is good on queenside castling when it takes the king one move to get to the b square?"
++ a3 after O-O-O weakens the position of the king. After O-O-O Kb1 is usually necessary, as the king is unsafe on the c-file and on the diagonal c1-h6 and as pawn a2 is unprotected.

"From what I understand, kingside castling is preferred to get the king away from the attacked center (c pawns are more encouraged to be pushed than f pawns, unless you go f4 or f5)."
++ Generally kingside castling O-O is preferred for 2 reasons
1) O-O can be done on move 4 as opposed to move 5 and it does not require a premature queen move.
2) It usually requires another king move to the b-file
The exception is if you want to launch an attack with the h- or g-pawn, supported by a rook on the h- or g-file

"I queenside castle 90% of the time"
++ That is strange. Grandmasters castle kingside O-O in 90% of games.

"So are fianchetto openings just not preferred just because it pushes that g or b pawn?"
++ A fianchetto weakens the position of the king and provokes attacks with the h- or f- pawns or with pieces aimed to trade off the fianchetto bishop and then attack the weakened squares. This weakness is compensated by the strength of the fianchetto bishop controlling 2 central squares and covering the created weakness.
On the other hand a fianchetto does not secure central squares for the knights, like the moves with the e- or d-pawn do.