for fire main you are good for now, sakura, sasuke and naruto will be used in sa and ninja exams (upgrade them to 3*) and sai will be helpful too in future, you get sasuke/naruto frags from chase mission on weekends.

change your formation to this:

x x x
Karin Fire Main Hinata
x Kakashi Clone

putting fire main in 2nd position will give you better chance to pull mystery faster (dont forget to use refines on your ninjas and fire main is ninjutsu based so mood should be nin+ when you do moods in future)

i am fire main from start, havent changed yet but seen many MB use guy, sasuke, kimimaro, jugo, kabuto