Integrating new Ts2012 purchase into Ts2013

Although not new to railfanning, I am completely new to this dream come true world of RWsims.
I just got a ridiculous deal ($10) for RW2012 from a third party store (fspilot(?).com) I had just gotten the amazing 2013 platform game during the Steam sale. I am having serious frame-rate problems due to an outdated core but am able to just passably play the game at Lowest Detail/Lowest Resolution (and it still skips; but I am resigned to using my imagination to smooth out the animation until I can afford a new computer
). When I bought the downloadable 2012 I just clicked 'Save to Desktop' when the installation window popped up, and the whole Zipfile labled 'RW2012' has just been sitting there because I have no idea how on earth it can be integrated with the Ts2013 I play through Steam.
Would anyone please give me some steps as to how to bring these two together and start expanding my world? I already bought some sale DLC routes/trains from Steam itself and these integrated fine, but the zipfile on my desktop feels like a whole other matter. I haven't even checked to see if the contents verify what was advertised as I am afraid that I'll launch it and make some kind of huge train wreck of a mess and be unable to play either one.
I know other people integrate all sorts of content backwards and forwards but I have no idea how to do it and I am scared to try. Firstly, will the older 2012 content just automatically 'subordinate' and run on the superior Ts2013 platform? (that is my hope of course) with all compatible trains and routes able to be Quick Drive'd or Free Roamed? Will my already slow frame rate be made hugely worse (and completely unplayable) by merging the two RWorks packages? Is this how the software works (using more 'core' memory) or is this simply irrelevant in computer terms: core-RAM=apples and oranges?
I would also love so much to access all this wonderful independently created source material that you folks produce from all over the world but if it doesn't come from the actual Steam website, how do I play it on my Ts2013?
Any and all help would be greatly appreciated.
I just got a ridiculous deal ($10) for RW2012 from a third party store (fspilot(?).com) I had just gotten the amazing 2013 platform game during the Steam sale. I am having serious frame-rate problems due to an outdated core but am able to just passably play the game at Lowest Detail/Lowest Resolution (and it still skips; but I am resigned to using my imagination to smooth out the animation until I can afford a new computer

Would anyone please give me some steps as to how to bring these two together and start expanding my world? I already bought some sale DLC routes/trains from Steam itself and these integrated fine, but the zipfile on my desktop feels like a whole other matter. I haven't even checked to see if the contents verify what was advertised as I am afraid that I'll launch it and make some kind of huge train wreck of a mess and be unable to play either one.

I know other people integrate all sorts of content backwards and forwards but I have no idea how to do it and I am scared to try. Firstly, will the older 2012 content just automatically 'subordinate' and run on the superior Ts2013 platform? (that is my hope of course) with all compatible trains and routes able to be Quick Drive'd or Free Roamed? Will my already slow frame rate be made hugely worse (and completely unplayable) by merging the two RWorks packages? Is this how the software works (using more 'core' memory) or is this simply irrelevant in computer terms: core-RAM=apples and oranges?

I would also love so much to access all this wonderful independently created source material that you folks produce from all over the world but if it doesn't come from the actual Steam website, how do I play it on my Ts2013?
Any and all help would be greatly appreciated.