1. If you're f2p, how did you get 4* Gaara at lv53? @.@ not judging, just curious.

2. Your current lineup will have to do for now until you get better ninjas. So don't worry too much abt it.

3. Don't worry too much about ranked battles, either, it's still too early for you. Focus on gaining power and getting good ninjas, then worry about those things later. There are useful threads around the forum, so you should look around a bit and figure some stuff out on your own. I did make a thread about ranked battles, but it's geared toward mid-late game, and you're still in early game, so that won't help much yet.

4. This early, though, I'd suggest you use use Gaara and Neji in ranked battles since they are quite good early game. Gaara will still be decent mid-late game, Neji will fall behind later on. And try to get Iruka, he's quite useful all around.

5. From what you have, I'd suggest a sustain team with Kabuto and Kimimaro (go ahead and upgrade his stars), Guy would also be useful here. Then go for a Gaara lineup. For now you don't really have much choices and option yet, so just try different things to see what works best for you and for now.