New to this, and considering one day adopting a certain 13 yr old

Hi, my name is Jason. First time posting here, so I am sorry this is so long. I have some questions and I am looking for advice too. Maybe my wife and i are just dreaming, who knows. We'll see where God takes us with this. A little about me and my wife: I am 36, she is 34, we have been married for 11 yrs. I have a BS in Industrial Engineering, I am manager of an engineering lab for a global company that designs and manufactures air conditioning compressors. We have two children of our own, a daughter who is 7, and a son who will be 6 next month (June). My wife works part time at the YMCA where we live. She works at the front desk. Somehow, and for some reason, this 13 year old girl that goes there for after school care has met my wife and taken a huge liking to her. Looks like my wife has really connected with this girl also. Soon after, my wife finds out that she is a foster child and has been for a long time. My wife can relate to her very well since she had a very rough childhood also. This girl is great! Great attitude, good manners, and does very well in school. She is always running to my wife to give her hugs. My wife and I have decided to mentor this girl (if that is the right term). We have gone to a class with dept of human services and got finger printed, etc. Now we can go pick her up on any day and keep her for the day only. It is nice to have her over to the house in a secure environment. She gets along real well with us and our kids. She is very loving. Soon she will be moving from her foster home and into a facility for foster children. Her current foster mother has 5 other foster kids, and the case worker says they are having a hard time with the mother (overall a grumpy, mean lady), so the kids are being moved. My wife and I got into a discussion with eachother last night about this girl. I am open to adopting this girl, and so is my wife. Not right now, but maybe sometime down the road. We would love nothing more than to give this girl a loving home with what we think are great parental figures. It would satisfy me greatly to help fulfill this girls dreams of going on to college, etc. The girls case worker said she would do everything in her power to help us adopt this girl if we chose to. The state pays for pretty much everything except something like $67. Then the state would pay $500/month until she turned 18. Money is no issue anyways, I would pretty much give this girl anything I could afford. Are we crazy? :D Are there questions we should be asking ourselves? Not sure we have seen this girls true colors, or maybe we are already seeing them. I am scared since she is reaching the dreaded high school years. Looking back on my own HS years, I wasn't exactly an angel for a couple of those years. With her past history of abuse during her childhood, I fear that this, along with the pressures of HS (fitting in, etc) could create a monster. Am I going overboard here? Just a little lost. I feel like the good lord has sent her to my wife for this very reason. Just not sure what to do or where to turn to now. Up until a couple of months ago we had never considered anything like this. Both my wife and I have very very big and loving hearts. I would hate to see this girl go through the rest of her life with no family or a place to call home. Worse yet, I would hate to see this girl end up in a foster home too far away from us to visit. We love her now like she is our own. PS - our own kids get along with her and accept her 100%.