Just to clarify by saying "none", do you mean none at all or just no additional ones other than Korea?
Korea is included, and others are being converted as we speak.
I'd love to dive right in to BMS, but I'm still running a P4-3ghz with an AGP card (I lack $,$$$ for a significant upgrade). Hell, my monitor is still a 19" VGA if that tells you anything.
You can always turn off the DX9 stuff and the performance difference should be minimal.
Can you dumb down the avionics until you can really devote the time to learn the details?
Not really no, but you can easily find training stuff on the net or in the included training missions which will quickly help you learn the basics and get in the air. After that you'll just be learning as you go.