First, most of the children in the system are going to have issues. If you want a baby from the state, at best you may end up with a crack baby. As they get older, the issues are going to be there, but almost by definition if they are in the system, it means they have issues that you and your family are going to have to deal with.
Second, as Ken noted above, you are inviting the government in to investigate every detail of your household for the next 20 years. Give up any idea of any but the mildest form of discipline for children that may have the highest level of social issues. No spanking/swatting perhaps not even "go to your room".
Remember, you are going to be dealing with children where no relative or friend is willing or able to take them.
I worked with a woman who fostered/adopted a mixed race sibling group. But her children were grown and out of the house, she had a mixed race marriage that matched the children, and she was well aware of the issues that those children had. It worked out for her, but she had worked with CASA for years so she and her husband went into the process with their eyes open, and they already had a very good relationship with the state workers from her time with CASA.