I just downloaded the demo for Reason as it seems like it’s full of synths and effects that would be fun to play with. I looked at the manual and I saw the pictures and information on Rewire but I don’t really understand all of it. Can samples played in Renoise be sent to Reason for processing? Can I sample sounds created in Reason? Is it only MIDI related? I saw that I could automate synths in other DAW’s. How does this work in the context of Reason, since it is full of all those patch cables and all?
Ty as always
Funny, I just logged in to ask a question about using Rewire between Reason and Renoise, and saw your question. I have only made one track with the 2 programs connected so I may do a poor job of answering your question but… I hope not. 
Anyway. In my opinion, the best way to look at it is like this: when you use Rewire to connect these 2 programs, you still (have to) do all of your programming, composing, arranging, and automation in Renoise. Reason’s synths will be external MIDI instruments, so you can kind of look at it like you have Thor, Subtractor, Maelstrom, blah blah as VST instruments to use in Renoise.
So, you rewire them together, go over to your Reason window and load an instrument and patch, and then you go back to Renoise to play it, program in your parts, etc. But like gova said above, Reason can only act as a Rewire slave here though, so you can’t send your Renoise samples and patterns into Reason and compose the song there.
With all that said though, you can add Renoise’s “Instrument MIDI Control” device to the track where you’ve assigned one of the Reason synths, and that will allow you to automate/tweak things right there without having to go back to Reason. For example… if you load up Thor in Reason and are programming a bassline in track 1 of Renoise using said Thor, you can use the “Instr. MIDI Control” device in that track (while still in Renoise) to change the filter cutoff (or whatever).
I hope that made sense - definitely didn’t intend for it to be 4 paragraphs. heh