I usually use a score editor to compose or arrange music and get the thing as good as possible after which I bounce the individual audio tracks. This resultant audio I then later import into Sonar to perform whatever necessitated DSP. Now, I am interested in utilizing ReWire inbetween the two. Before I actually attempt to do so, I especially want to know if there are any important things to consider in general, so what are these matters to consider? Furthermore, specifically, as I have never seriously used ReWire, I wish to know whether ReWire detects tempo changes and synchronizes everything well between the two programs.
 
As you may perhaps notice, my current way of working is fine and works well for me. I am wondering if ReWire would improve the situation. In fact, better yet, let the Sonar developers incorporate a certain good notation editor very well into Sonar so that I have no need to use the standalone score editor nor ReWire in the first place

I have not used ReWire with a score editor so I can't address that specifically. I have used ReWire with Ableton Live 9 and it works extremely well for me. Yes tempo changes were picked up.
 
If your current notation software supports ReWire I would just give it a try on a test project. If it works, then great if it doesn't you are only out the time you spent. On the other hand if it would require an update to your notation software I would recommend trying to get a demo version of what ever it is you use and still conduct the test.
 
My guess is you will be pleasantly surprised at how well ReWire works.
 
Regards