Yes that is very natural. But for selfish it would be. "She is so selfish, she always wants her own way" "She is so selfish, she only thinks of herself" "She is so selfish, everything has to be centred around her" "She is so selfish, it's all about her" <-- more informal and street colloquial/idiomatic The way she wants it/how she wants it = is used more for being particular "She is so fussy, everything has to be the way she wants it" "She is so finicky everything has to be how she wants it" "She is so hard to please, everything has to be the way she wants it" "She is so fastidious, everything has/needs to be done the way she likes it"

Yes. It sounds good. I wouldn't recommend any changes.

100% perfect :)