My goodness they are cute!! Be forwarned... take LOTS of pics!! They grow super duper fast! i have four ducks, two are 2 1/2 weeks old and are huge and the other two are just about a week old now and are catching up to the others. They double their size in a week, so get lots of pics while they are young and fluffy!
I wouldn't worry too much about the heat either. I've had to lower the heat in the older duck's brooder to about 80 already because they never went to that side of the pen. The didn't like it so hot. Go by their body language moreso than the temperature gage.
That is so true about the heat, we had a poster who lost her ducklings because the heat was too high. even my chicks have done better with the heat not being so high.