My daughter is also an Asian-American adoptee, and also very bright. She just turned 6. We have found similar acting out behaviors (although she is pretty shy so does it more at home than in public). She came to us when she was only 4 months old, so I have never had deep concerns about attachment, but sometimes I wonder if she is acting out to test just whether we will be there even if she is naughty. Even as we are imposing consequences, we remind her as Passthepotatoes suggests that she had a bad day, there are consequences for behavior, but that we love her no matter what. Whether this is working, I really can't tell (she still has some big blowups which are unlike anything my DS ever had).
My MIL, who raised 4 kids, including 2 transracial adoptees, and who is a very wise parent, said that most of the time it is just differences in kids, and to not over think it - meaning that a lot of times you will want to pin behavior on adoption or race, when really it is just a particular kid being a stinker. The fact my daughters blowups almost always occur at bedtime suggest that she is using them as a delay tactic and likely she is tired and more likely to act up (she knows there are many issues that may arise due to adoption, she just is pointing out that usually, they are not related).
We are lucky that we live in a fairly diverse area, so she does she a number of Asian people (including a close family friend and her doctor) although there are not many Asian kids in her school, it is approximately 50% students of color. We have not had any negative discussions about appearance at least.
Good luck!
