Hi Lisa, each orchid grower will have a preference for their orchid media. Personally I really hate sphagnum moss, I can never gauge properly when to water, it holds water too much and too long.
If those were my plants, I would remove the sphagnum moss, and make a thorough inspection of the root system. If there are dried out roots, brown and very brittle, cut them off. Make sure you sterilize your scissors or whatever thing you use to trim them out. I think your orchids are Phalaenopsis, so I would recommend you use chunky orchid bark mix till you get used to the plant. Phal roots are rather thick, so it really wants lots of air circulation at the root zone. So make sure your container has good drainage holes at the bottom and side holes for further air circulation. I would position the plant at a slanting angle in the container, it really likes it that way. Typically before I do the repot, I would have already presoaked the new media overnight. Some again have their own preferences about this, either they presoak the new media or not.
During repot, carefully try to put the roots inside, and shake in the new media. During the first few weeks I dunk water the container for a few minutes, up to root zone level only, not wetting the leaves and then let the water drain out thoroughly. It takes awhile for the media to be moisture retentive and I always run the ceiling fan after watering. Good air circulation is what it likes. Now as to watering, oftentimes overwatering is the primary killer of orchids. You have to adjust watering as seasons change..less during cold season, and a bit more during the warmer months. Each orchid grower has their own style. I do not spray mist my Phal leaves and they thrive well. Some would spray mist them a lot, but you have to consider where they are growing the plant, oftentimes it is outdoors. Orchids love the outdoor interaction a lot, but in our indoor microclimates, it will adjust differently.
As to fertilizing, weakly weekly is being done by most, meaning half the strength of the fertilizer. Too much will cause fertilizer burn on the roots and leaves.
Good luck on your plants! Hope they recover
Just adding: the first photos of your orchid..I agree with what the others have said..it is better to start anew..it is kaput.
