The best thing you can do with a stock CS-3 (aside from modding it) is to keep the "Sustain" knob down around 9:00. And/or use another pedal (like an EQ) to lower the level of your instrument going into the CS-3. This will effectively raise its threshold, making it more generally usable.
There's no "correct" pedal order other than whatever order sounds good to you. That said, I might put the comp
in front of the overdrive, just because compression can sometimes take the edge off of dirt effects; and I might put the comp
after the synth, because synth sounds can sometimes put out some big resonant spikes.
You might be better off with a different comp, unless you feel like doing some soldering.
Also, just FYI the ODB-3 is not capable of a "slightly overdriven sound". It's pretty harsh and extra-dirty. You'll defo want a different pedal if you want subtle overdrive.