Splitter Channel workflow
The splitted channel option in calibration is only needed if you want to combine OSC/DSLR camera data with monochrome channel data. Then you would need to split your RGB data. And process the splitted channels together with the monochome channels from the monochrome camera separately. So integrate all red data, then all green, then blue, then register the R,G,B integrations and then import them into the RGB Combine tool to create a final RGB image (or LRGB for instance).
Regarding the outlier rejection filters, check this:
Let me know if this answers your questions.
Main developer of Astro Pixel Processor and owner of Aries Productions