For characters, some stuff that I currently have learned in a nutshell about them is this :
High (1v1) to Ridicoulous (1v3) Damage but Medium Ground Mobility (Except when you dash, but in this case, her normal walk, which I assume is in par with Parasoul.), Cerebella.
Par on every aspect (Damage and Mobility), Filia.
Air control, Painwheel.
Shoto-based Support character, Valentine.
Charge character with Armor moves and very high damage, Big Band. (I always call BB 'MikeZ's Iron Tager', is that bad?)
A mix between command grab characters and zoning characters, Fukua.
Opponent control at stage with her Serias, Squigly.
Zoning character with powerful moves without needing any Quarter Circle moves to actually do the combos, Parasoul.
Airdash and quick combo inputs, Ms. Fortune.
Mostly ranged attacks and 'pressure-the-opponent' style of gameplay, Peacock.
and other characters which I can't describe since I haven't played them yet.
You just need to pick which one that suits your playstyle most and learn/master said character until you feel the need to learn about the others.
Also, regarding the tutorial, you will learn MANY things about fighting games as it teaches you the basics, from attacks, movement,and blocking, to a more advanced level like blocking and punishing mix-ups, Cerebella's Ultimate Showstopper, chaining combos and cancelling into airdashes, and much more.
Though what lies behind your gameplay is your experience. I mostly train with bots at Hard - Nightmare just to warm up before I take on people in quick matches. It sure helps you if you already know of a character you wanted to play and still wanting to learn the mechanics of said characters' moves.
That's all I can do to help, anything wrong, please tell me, because I am a master scrub at all fighting games as of now.