RE: Control surface trailing edges
Torino!
NACA research has shown that the perfect trailing edge is a razor sharp trailing edge. The NACA research also showed the next best was a square trailing edge, as much as 3/16" on a 12" section. The worst is a rounded off section, the way many models are done!
For one example of a square trailing edge an a full size aircraft have a look at this (rather poor quality) photo of the trailing edge of a Saab Draken fighter aircraft.
/Red B.