Thank you, I haven't seen this one before. So the actual coop size looks to be 53" x 56" (115" total - 59" for the run) so around 20.6 sq ft, assuming the nest boxes aren't included in the length measurement. So coopwise that's about enough space for 5, maybe 6 chickens. So maybe if you add a...
Editing for clarity: I forget to mention... I have never had ducklings, so the advice below is strictly for chicks. I know there's a few differences in diet and water needs, but I believe ducks need more space than chickens?
A heating pad works fine as long as it does NOT have an auto shut off...