Hi Doug,
Thank you for writing in.
1)Use the HR you settled at the end of 15min warm-up and before the first 30min of the test, not the average of the first 30min.
2) Not a problem. The total duration HR is above AeT is very small relatively speaking. And, for almost everyone, a little bit of volume above AeT is OK, even if you are very aerobically deficient.
Thanks, and happy training.
-Seth