It is great that she has a really good friend! You are lucky:)

Sounds like you can do some more observing and figure out more about friends, names, and hearing from just knowing what to look for.

Keep in mind that for some kids with CAPD, just a small amount of background noise (like a lot of people breathing, paper being shuffled, a fan, a dishwasher, the hum of car driving down the road) can play a big role in hearing. So look for truly quiet environments and compare them to those with any background noise and those that are loud.

Some other books about CAPD:

1. There is a chapter on auditory processing disorders in Eides' book The Mislabeled Child http://www.amazon.com/MISLABELED-CHILD-THE-UNDERSTANDING-LEARNING/dp/B0016IYQV4/ref=pd_sim_sbs_b_17

2. When the Brain Can't Hear : Unraveling the Mystery of Auditory Processing Disorder by Dr. Bellis is a good full book on this topic and explores how it manifests at different ages and in different people, how to test, and how to deal with it.

You are asking questions about when to worry about things you see in your DD. It can be so tricky to distinguish a problem from a PG trait. For questions about social issues, peers, and figuring out when something is normal for a PG kid and when there is a problem to investigate, I'd suggest Misdiagnosis and Dual Diagnoses of Gifted Children and Adults: ADHD, Bipolar, Ocd, Asperger's, Depression, and Other Disorders by Webb et al. http://www.amazon.com/Misdiagnosis-Diagnoses-Gifted-Children-Adults/dp/0910707677 This is a reassuring book to refer to when you have a middle-of-the-night fear:)