Death seems to happen almost overnight. If in doubt, no leaves, no water, is probably safer. I regularly forced my plants into dormancy by cutting off any remaining leaves in November. Catasetums will do well in a variety of potting media so long as they are fertilized and watered regularly. To simplify your watering requirements it is probably best to use the potting medium which has been used for your other orchids.
Sphagnum moss works well for most people.
Cow or sheep manure mixes work well also. I think overall that growing the plants in pots is the better method. The plants are not frost hardy and should not be exposed to temperatures below 40 degrees Fahrenheit when in active growth. In parts of Mexico the plants do grow in areas which do receive frost, but the frost is light and rare and the plants are dormant during the times when they might get frost. When a new growth appears at the base of the pseudobulb, is the time to repot the plant.