You dont have to install any apps than chrome to start learning it. If you need IDE then use your notepad as a starter or download free IDE online...VS code is just perfect.
1. As front end scripting languge using it along css and html. You can also use frameworks like Vue.js, React.Js, Angular e.t.c. All those frameworks are faster because of the way they handle DOM drawing is quite different, we talk about that tech one of these days.