I've only had to deal with colds from shelter. Both Eleanor and Thumper had slights ones from PetSmart. Their appetites were pretty normal after a day. First day both didnt' touch much food.

Dewormer, I had to give Skinny that pill (as a precaution) it didn't slow him down at all. Eleanor and Thumper already had the pill before we got them. Cant help you on that part.

I would certainly ask shelter if he had potty problems while he was there.