I don't have foster kids but I have freinds and a cousin who do.
Here is my take on it. I might be wrong, (doublecheck me) but this is how I understand it:
You can either do a private adoption where you hire a lawyer, pay thousands of dollars and the state has no jurisdiction to come into your home, check on the child, or anything like that. You get no money from the state. You get to raise the child how you want to raise them with no interference.
Or you can adopt through the state, and be beholdent to them. They will be coming in your home for "visits", asking questions, giving you perameters on how you can discipline,(at least that's what a freind who has an unruly boy told me- they won't allow you to use any punishment like spanking). Sometimes the state 'overlooks' or fails to inform caregivers about handicaps/medical issues. I think they supply money to foster care families, and will pay for special-education classes and things like that.
Your lack of privacy with the government should be a big concern. I have thought about adopting myself, but because of the power that the state has over your family privacy, I opted not to.
Further, the way you are allowed to discipline a foster child will rule how you will be discipling your biological child. (you wouldn't want to treat the children differently).
Human beings are creatures of habit and old habits die hard. If you adopt a school age child, be ready to invest ****ALOT**** of time, energy and resources into this child for re-training and other issues, because they are going to need it. On the other hand, if you adopt an infant, and lets say, the mother was an druggie/alcoholic, you probably won't be able to see possible medical issues that would be arising later.
Many of these kids have issues with attachment (especially if they have been in a few foster homes already)which can raise the stress level in your home substantially. Stress in the home puts added burden on every relationship in the house, even the relationship with your husband. Before you adopt you need to ensure you have a strong marriage. I can imagine your biological child might feel slighted to have another child move in and take away his mommy time. You will also be putting added work on those support systems around you. For example, if the child ends up having medical issues and you need to be spending a lot of hours in hospitals, do you have a "willing" support person, like a mother, who can take your biological kids during these emergency moments or overnight? When you take on these kids, your entire family takes on these kids. You all need to be persons of endurance and patience for the task of foster parenting. My hat goes off to those who can do it!