One thing I am wondering about is if surface detection is not averaged out during actual combat. It at least seems like having a single ship with high detection along with ships with poor detection is good enough in combat.
Of your fleet, or task force set on patrol?
If it's the whole fleet, then it would be better to have purely spotting fleet with no strike forces inside, as strike force would have lower detection.
This guide answers your question.Coordination -> Truth. No idea how it works. Likely its based on the size of the fleet you are using. I was never able to get that value above or below 100%......