Will old biometric data be retained?

Will people who have already given biometric data in the past – e.g. for a temporary visa that has now expired – be automatically registered in the system, and exempt? 

No, the fact of having given fingerprints and photo as part of a past visa application will not exempt people.

Such data given to French consulates is not expected to have been retained.

If, however, you are entering the EU on a short-stay Schengen visa for which you provided fingerprints you may not need to give fingerprints again.