Keep in mind that raising "hurt" children (those from foster care) is definitely different that otherwise. While they face normal "kid" issues, they also have a lot of other things that can sideswipe you if you are not ready for them.
We adopted a sibling group of 4 about 9.5 years ago, and were greatly surprised last fall to face some major issues. We have adapted, but our "smooth water" in the preteen years disappeared. Had we been looking better, we would have noticed it earlier, but we were a bit naive, as you almost have to be to consider doing this.
You can make it, and they are wonderful children, you just need to know all you can.
Brad