Have not wormed flock. And I have not a clue as to whether they were vaccinated at the hatchery or not. I was doing some reading on Mereks and that is a possibility, but it didn't seem to be the best match.
While the straw was definitely damp, I didn't notice very much mold as it's been too cold. Today is warm (40 degrees) and the snow is melting like crazy. I am planning to get a bail of hay today and put in. Perhaps straw wasn't the best. We used hay exclusively for the first 3 1/2 years and for some reason switched to straw in the last 6 months.
No space heater in coop, it is the electric heat wire around the waterer.
One of the two remaining sick ones (or ones showing signs of illness) is nearly dead, and there's still one not doing well. The other 10 hens, the rooster and the two ducks seem to be fine.
Thanks again for all the input!