Hi youri,
I’m not sure why you keep asking similar questions in different threads (details not aligning):
It would be better to report back on suggestions for those similar questions in other threads. Unfortunately, my crystal ball is in the workshop for maintenance at the moment. Next week, when it’s back, I can look in there again to find your answers… 
Whether you need to group your images or ungroup them or in which order is for you to find out. It depends on the object, your desired accuracy and the image set.
Do you mean “Group calibration by exif” in Workflow - Aplication Settings - Import Settings? This, as the location indicates, only influences the result while importing images - it automatically sorts them into calibration groups according to the exif info about the focal length. You can always change that manually or by clicking in 1Ds on “images” (the word, not the “+”), then a secret menu is revealed where you can group and ungroup all of them with one click.
Merge components only is something completely different - it just tells RC not to bother to try and add more left over images to any component, but only to merge already existing components.