Sorry, here in support I can only inform you on how the software operates today. If you have suggestions to change that, please post your suggestion in the Feature Suggestion forum.
I would advise assigning a group to the permissions you want then assigning that to each individual moderator.
The intended design would be that if you provide an individual member a moderator selection, it will indeed overwrite and group selections. If you have suggestions to change that, please post your suggestion in the Feature Suggestion forum.
There is not really something for this at this point in time. There is internal discussions about permissions and making it easier to see what groups or members have access to what. However, nothing is set in stone at this point in time or can I guarantee a release point of that. Due to that, like the above, I would recommend creating a suggestion for this as well. This way we can stay on top of it.