With Modern Air Combat coming out, I understand it comes with scaled-back versions of the existing maps. If I buy any other maps, will I be able to use them with MAC aircraft?
Also, is there an advantage to running DCS World in its standalone version, or the Steam Edition?
From what I understand, MAC will be sold as a module, so think of it as Flaming Cliffs 4 but with more sensible name 
So you will (probably) be able to use them with your current content. Moreso, FC3 users will get discount on MAC as it contains some of the aircraft featured in this new package already.
The advantage of using standalone is that you will get all the fixes (along with new bugs) faster. Most modules gets released first on standalone, then on Steam version.
Okay. I think Steam only recently updated DCS:W to v2.5.4, so I’m just trying to figure out what to do. I know that you can now migrate the older Steam keys to the standalone version, but only if they are the Starforce-protected ones.
MAC is still a bit of an unknown, we have only guesses. Things seem to be going in an unexpected direction, so don’t bet on it being one thing or another just yet.
This. MAC/FC3+/FC4 has changed in scope and substance a couple times since being announced, best to just sit tight.