Charles' kit is incredible. But if you don't like a unit you don't like a unit, it can't be helped lol. I've tried upgrading highly-rated units early-game that I wasn't into before, I just ended up benching them. Learned late-game how much their utility were OP later. Still benched, lol. Just do units you like.

For W11 you can use Karin with TG, Angie and Dizzy. But you only need them at 5* so no need to 6.

Honestly you have a good core team so just do whoever makes you happy to use.

In general you'll need 6* amomo at some point because you'll use her everywhere else later on. And DPS wise, aside from Ken/Charles, I'd say C Merc, Violet and Vildred. You'll never really use Kiris past some cheese levels and she can do those at 5. Clarissa is outclassed by Bellona so redundant. Luluca is like a weaker Dizzy/Bell. I liked Kise's design a lot, but she has been hard to build so she's perm benched. If you like her design though she's an option too if you can invest into her.