I would steer clear of DCS and look at Il-2 Battle of "X" instead.
In DCS:
1. The AI doesn't have the same FM as the player, and can do stuff which make you feel your fighting against a possessed UFO. It doesn't feel the AI is playing the same game as you are.
2. The damage modelling is extremely rudementary: The aircraft got hitboxes with health points and your job is to fire enough rounds into the hitbox until the health is depleted.
3. Both the Normandy 1944 and WWII asset pack are rife with inaccuracies and bugs, and have been abandoned by the devs mid-way through.
2 weeks ago I tried out the K4, and I would steer clear of that aircraft as well since the "systems modelling" doesn't work like in the real aircraft/is bugged (pumps and gauges bugged and stuff like that), and the DCS FM engine freaks out when you put the aircraft in a storm or outside the envelope.
There also isn't any real campaign for WW2 aircraft, meaning the only options you have are stunt flying, target practice or multiplayer air quake.
In Il-2:
Il-2 seems to have a major problem with the P-51 flight model and ground behavior of aircraft, but beats DCS in all other aspects.
You can currently try out all DCS WWII for free though, which I definitely recommend to create your own opinion about DCS