Need info and help with my team construction :X

[Aika]

Hi, i joined the game 3-4 days ago and this is the state of my team:

Now, i need some informations, if you mind :X, i know that Yuna is C rank in the tier list, but i don't know what it should be better for me right now since i did she 6* and with 6-7 -cost.
I'm okay with this team for now?
I bought even the 3000 medals pack so until sunday i can join every dungeon i want, do you know if there is some unit worth to be farmed? Maybe Water Sora final form? There he is in this version? (i didn't played the JP, just readed some post).
I'm working on a fire team too, with the Treasure Trove, where i'll use KH Riku, Hercules (since i've many), KH Riku Black Coat, DiZ and Goofy/Wakka, is it good?
The question i want to know most (and i already asked once xD) if i can farm some units 1*, can i?


Thank you in advance for all the answers.

 

[Aika]

Bump :<, Can someone help me? :X

I've an update, i did yuna with skill at 5, now i'm trying to reach 14X of cost so i can upgrade Sora to 6* too, any tips about the team? Is good or i've to change it?