Donor Perfect to Constant Contact export

Two part question-

Can anyone tell me when Donor Perfect exports names to Constant Contact where does it put them? Is there a way to designate the list to go to? Is there a way in Constant Contact to tell whether a contact was exported via DP or organically entered via Constant Contact? I have talked with several experts on both sides and no one seems to know for sure.

When you purchase Essentials (as we have) is there a limit on the number of contacts allowed in Constant Contact or are you charged by various thresholds as you would be if you purchased it separately?

Thanks