Travelex
I can confirm to you that the 66L part will be the aircraft call sign used with Air Traffic.
With regards to the flight operating up to ABZ, it may have been that the fault resulted in passengers not been allowed to travel on safety grounds, but could be operated by flight crew to get the door fixed at a more suitable maintenance base with the correct parts.
The reason Eastern are quite expensive is that they operate with small numbers on some flights and that the busier flights subsidise the quieter ones, so they would not cancel your flight because of only 3 pax.
At least you did get to ABZ and not at your own expense, when some carriers would have dumped you with a refund and told to return in 3 days time when the next flight operated