You will need to petition the court in the county in which the juvenile/neglect proceedings were held in order to regain custody of your children. You will have to show that pursuant to the 12 best interest of the child factors that it is in the children's best interest to resume a relationship with you. Normally, in the juvenile/neglect area, the Court's goal is to reunify the children with their parents in lieu of any foster care situation.
No, you would not be directly responsible to pay the loan if you did not co-sign the loan, just by virtue of your marriage. There is not privity of contract that you have to repay this debt with the lender. If the loan goes into default and your husband is looking for you to repay it, then you would need to contact an attorney.