Sounds like she has a very good temperament. Maybe you can consider going to a training program to get you started on basic training techniques. I love clicker training - have had amazing results with it.
I don't know too much about service/therapy dogs tests, but I
think in addition to sit and stay, they'll be required to do other tasks like 'leave it' in a very distracting environment and follow the heel command to a tee (forgive me if this is incorrect info
).