Thank you everyone for your insights and suggestions!
I had the meeting with DD's teacher this afternoon. While it didn't go as well as I had hoped (nothing super incredible was planned), it was clear that we are both of a similar mind for what DD needs for the rest of the school year. More challenges, more encouragement, and less busywork.
Teacher was baffled that DD would hate (or say she hates) school so much, as she does not act that way at school. I briefly described her before-school requests to skip school, and her after-school meltdowns. At school she's charming, helpful, friendly, and an all-around Good Kid, although the teacher did say she saw hints of intensity every once in awhile.
We talked about upcoming projects, and DD's hope to learn multiplication (which they will cover before the end of the year). DD will be allowed to work on her own projects at school, provided she do at least some of the required work (and the teacher has been systematically tossing stuff out from the regular curriculum because it's too easy or boring). So she won't exactly be taught a bunch of new stuff, but she is being allowed to skip a lot of the really easy work.
We brought up homeschool, and whether the fact that DS was at home was affecting DD (yes). Teacher is okay with keeping DD home now and then to experience homeschool (apparently DD told her that she thinks DS stays home and plays Minecraft all day!)
The teacher seemed to think that DD got along well with a handful of girls, and didn't think bullying was an issue. I will continue to monitor this, although I think it may be difficult. Teacher gave me an account of what happened during recess today (positive), and DD gave me two differing accounts of what happened (one negative, the other mixed). What actually happened, I have no idea, although I'm sure there's a grain of truth in each story.