If people don't mind, I've gotten a decent bit further now, and some more advice would be very appreciated. I just managed to beat Castle Retake this morning. My most-used units look like this:

Katie 50CC30
Iris 50CC30
Soma 50CC30
Cloris 50CC30
Bashira 30
Calliope 30
Grace 42 (waiting for a platinum armor)

Just yesterday, I hit my goal of getting to Phalanx 2, but Cloris and Calliope aren't strong enough to beat all of them on their own; I can 2-star the mission, so I've been using my stamina to get their affection up. Well, I also hit 50 SC, so I thought I'd put a few points into upgrading my army capacity and rolling on some new units to upgrade my stamp card. Here are the non-silvers what I got:

Black: Altia and Elyse
Platinum: Agnes
Gold: Bernice x2, Fedora, Momo

Basically, now I'm much more conflicted about the best way to continue from here. Should I continue to focus on my established team until I can get to Fiery Oasis, or should I start leveling up the new characters? Also, what's the deal with necromancers?