Personally I think in World War 2 in general , pilots did not know the true extent of their aircraft damages at least 99 percent of the time. Classic example is the legendary American Ace Robert Johnson, who after an encounter with Luftwaffe ace Egon Mayer sustained over 100 hits from machine gun fire, and lived to tell the tale. Upon landing back at his base in England (which was an absolute miracle for a P-47) the authorities stopped counting bullet holes after they reached 100!
As for the sim, in combat, you won't be around long enough to read damage texts. Thanks to the folks at microsoft. At least you know what you're really up against when you get hit. However, your aircraft will tell you when its done. It will either sieze its engines, burst into flames, or just fall out of the sky regardless of what you do. The only thing that can save you is altitude and intuition. Know when to bail out and when to ditch. Whichever side you choose, don't worry, there's always a replacement aircraft for you to fly.
Hope this helps
Be sure to download and install the ETO if you haven't already - it's flight simmings best kept secret! 
