Welcome lovewing! Great that you found the bulletin board; there are lots of people here willing to help you with any questions you might have.
As far as realism comparison to WWII Online, Aces High it is not a two-sided game in the Main (Melee) Arena. It's a 3-sided (Knights, Rooks, Bishops) free-for-all, and all sides have access to all planes. So you could find yourself in a Spitfire dogfighting a P-51 or P-38, which isn't realistic.
The flight and damage models in Aces High are likely better and more accurate the WWII Online's, as I've heard air combat took a backseat to ground combat. But you'll have to judge that for yourself.
You'll have so many planes to choose from to fly here, from early War right through to the very end (Ta-152 and Me262, and B-29).
Enjoy!