Here is an example of what I would like to do:

I have a song open that is playing a 4 bar loop at 120 bpm.

I open another song, that is set at 120 bpm.

What I would like to do, is to press play on song #2, and have it automatically go to the bar+time that song #1 is currently at.

Any ideas?

I want to DJ with Reason and open a new song, fade it in, and then fade out and close the old song.

Any suggestions or advice are appreciated!!!

You cannot syncronize different Reason instances. I recommend, to render your songs as WAv files and then use either a DJ software or Ableton Live to mix them. That would also save you lots of resources.