Ok, so here's what each character actually does:
- Xi: Generates money. Think Sunflowers from PvZ. Yellow warpy money things come from her. Blue ones come for free.
- Rey: Shooty shooty shoot shoot.
- Vanda: Blocks damage. Gives none back. Basically a meatshield.
- Han: Sacrificial meatshield. Has no damage or health, but instastops whatever enemy hits her first. Good in early game or for slowing glasses dudes.
- Amelia: Like Vanda but hits back. Seems to do more damage than rey, but only on her square so no use putting her behind shield lady. Actually not much point for shield lady except shes cheaper
- Lisa: No idea, I've beat lvl 9 and I still didn't unlock her so I've never seen her. Has a bow tho.
Lvl 9 can be won but it's hard. I tend to spam xi early on out the front, build up shootys at the back and then as cash becomes less tight I trade xis for amelias. I dont think you can remove people manually, but theres a bunch of robotic blokes who'll happily help out.
I'm loving this game devs. I'll probably end up on your patreon if v0.3 is good too. private tier tho cos im a cheapass