NAP architecture/interoperability Issues

I am trying to understand the Network architecture of the current
NAPs and the technology/interoperability/operational issues that
they currently face. Thus I have a few questions:

1. Is FDDI still used within NAPs?

2. How prevalent is ATM in the NAPs? What Interfaces
    are prevalent? What are scheduled to be phased in?

3. Are ATM DS-3 DSUs still used?

4. What are the issues to deal with in peering with the Route Arbiter?

5. What are some current problems facing the NAPs?

6. What are good repositories for NAP information?

7. Have there been any interoperability issues that have come up in
    with current or new technology?

Mike Maszczak