Note that it is up to the airline to prove a reason for a delay.
e.g. With the OP's first issue, it is not sufficient for the airline to simply state "Air Traffic Control". They must provide unequivocal evidence to support that statement in order to claim "Exceptional Circumstances".
Moreover, with the OP's additional issue, it is not in itself sufficient for the delay of an inbound to be caused by "Exceptional Circumstance" for a claim to be denied.
There is a lot more in this thread from the BA forum:
http://www.flyertalk.com/forum/briti...61-2004-a.html
In relation to DL and the regulation, it basically applies to any journey departing an EU port.