My Mini Gal, I don't think you're hoping for too much. No matter what her personality is, if you are patient, consistent, and dedicated to making things work (as you certainly sound like you are!) you will have beautiful, lifetime partnership.
I always describe Max as "sensitive". He isn't a snuggly, in your pocket horse, and he isn't a mellow, do whatever you want to me and I'll fall asleep horse. He used to be hard to catch. His basic nature is to be reactive and somewhat more hot, even as an 18 year old. My daughter and I have to take that into account, and take some things more slowly and carefully. And yet his personality also makes him smart, careful to read and respond to cues, and he has a strong work ethic. Once he learns things are okay, he accepts them calmly, which has made him great at everything he does, from pony rides to driving obstacles. I've owned and worked with other horses with different personalities. Just like people, you love them for who they are, and work with their strengths and shortcomings.
All of this is just to say that no matter what her basic personality turns out to be, I don't think you should worry about it too much. Even a hot or sensitive horse doesn't have to be a "nutcase" or badly behaved. And just because a horse has a mellow personality doesn't mean that they will be free of annoying or dangerous behaviors. So much has to do with how we consistently handle them.
You have a great adventure ahead of you! Best of Luck!