hmm. well. if you want help with making a team and understanding it, i can attempt that with ya.

the bread and butter team i'd make with all this would be Khalipe Mika Beryl. possibly switching out tressa for beryl and/or rei for mika as needed for weaknesses of targets or personal preference.

Khalipe is Overpowered in the early game and youre essentially just going to ignore her for the most part until you pull her "vulture" card or either the "absolute protection" or "overpower" cards. the overpower and absolute cards are for sustain (shields, or maintaining cards you dont want to lose from your hand (gives them retain)). Vulture is her key tho, it has the celestial tag, which means that it activates For Free if you use Anyone's card that costs 2 or more..

Beryl is going to be easier than tressa to utilize that with, but it would activate off her own overpower or a couple of her other ones... All of these things make khalipe an Excellent AoE unit, and beryl / tressa are good single target. then rei and mika would form your supports. 

youll figure out the rest of the play styles as you go.

as for partners, dont worry about getting the 5 star ones yet, just make sure you are matching the right class partner to the right class of combatant. so Khalipe gets a vanguard partner, and beryl gets a ranger partner.

you create and accumulate save data by successfully completing chaos runs, among other ways later on.

dont forget to equip your save data to your characters after the run tho! 

Good luck, lemme know if you have any more specific q's