What kind of moss, Sphagnum? If it is Sphagnum then that holds moisture, they don't like to dry out so with your weather you need to decide how often do they need to be watered. The next time you need to water, pick the pot up before you water and feel the weight, then soak the plant for awhile or water the pot, wait for that water to drain out then water again, do that 2-3 times. Once you are done pick the pot up and check the weight, after that before you water check the weight of the pot that will give you a good sign, is it ok or does it need to be watered. As to fertilizer I can not really tell you what is best, other then the time released (13-13-13) that all my potted and mounted plants get each spring any other fertilizer I use is organic.
You should read the following;
Catasetum series on AOS it will give you lots of information that will also help.