It sounds as though your sim background is very similar to mine in terms of coming predominately from WW II prop aircraft. If you are a flight sim fan I'm going to go out on a limb and say you will love DCS- the products are very good. (They are also open to 3rd party developers and you will find that out if you pursue DCS.)
The previous comments pretty much sum up the essence of what DSC World is but what is also interesting is that you can pick and choose which platform you want to purchase. If you are making the transition from WWII aircraft the A-10C is probably a good place to start. I tried to work myself into modern aircraft with Falcon Allied Force several years ago and, as good as it was, I was utterly frustrated. The manual and tutorials were there but I just couldn't get used to the intricate weapon and sensor systems. You shouldn't have that trouble with the A-10C; there are interactive in-cockpit tutorials with voice-over and clickable functions to get your feet wet. In addition, there is a 600+ page manual included in PDF format.
DCS also updates (automatically, if you wish) all of their modules which I feel is a huge benefit.
The sim also comes in 2 versions- game (arcade) and sim which you can switch between very easily, although I don't think many people bother with the game version.
Be prepared to spend some time with this- I check the forums (and youtube videos) regularly for hints and tips. I remember reading a post somewhere that you will spend about 10 hours or so (real flight time/real life time) until you really start to get a handle of things.
You should have some sort of flight control with at least some HOTAS controls- I have an old Saitek X-45 with flight stick and throttle and its good enough for me but all of the newer sticks are much better suited to the complex avionics and systems modeled in all DCS modules. The old X-45 worked fine in IL-2 but in A-10C, more buttons are better!!!
Take the Plunge...You'll LOVE it!!!!