Hi there,
This is not meant to be legal advice because I'm not a lawyer but I wanted to share my personal experience with something similar to this in family court. I've seen firsthand that the general information you're seeking will not be as impactful (or may even be considered "irrelevant" in court) as the specific impact on your stepdaughter. I presume that she is involved in counseling. Getting a letter from the counselor stating that in his/her professional opinion ________ (the information you can obtain from these great resources above) results in his/her professional opinion that your stepdaughter should be in the custody of you and your husband. I've lived through this nightmare as far as judges understanding the impact of domestic violence on children and they don't get it, so if you can get information personalized to your stepdaughter it'll give you the best chances. Secondly, I'm not sure what state you live in so I don't know if this applies but requesting a guardian ad litem for your stepdaughter is also really important.
I'm so sorry that you all have to endure this. I know that pain and it is hell. I hope that the judge does what he/she should do and protect your stepdaughter!