Many sceneries are being uploaded that say RWY12 required. Can I just download the libraries without having to download and install the whole program? I am not going to be creating or placing objects on my own.

That's a common misconception about RWY12. You do NOT need the entire program, all you need is the associated library BGLs that the scenery developer used.It would be easier and much nicer for 3rd party developers to include those libraries with their add-on sceneries. I know that as a 3rd-party developer myself, I always do.-Steve