Hi there,
The damage on the Brownings is correct.
Use target values depending on the facing of the attack, as normal - there will be no such thing as top armour in BF Evo, and they do not get the elevated rules. However. . .
We are looking at the effects of allowing aircraft to use the elevated firing position rules - if we decide to go ahead, it will either appear in the Player's Guide or, more likely, the Air Power supplement (where aircraft receive several new rules, and are balanced to receive them).