New user with questions about "my music"

[adisonidle]

Hello!
Relatively new user here with a few questions. If I add a song to a playlist, will it automatically added to the "songs" section of my music? Or do I also have to hit the little checkmark to save it?

Is there anyway to rearrange the order of playlists? Using an iPhone, the playlist I access most is all the way at the bottom.

I'm considering using Spotify is my primary music source rather than iTunes. Is anybody doing the same? Has anybody had success using Spotify for all their music needs and not worrying about iTunes and such?

[MauriceMV]

Nope, when you add a song to a playlist it doesn't automatically go onto the 'Songs' page under Your Music. If you want to do that you need to click the + sign to the left of a song