With Dendrobiums, you will want to remove old dead canes to keep the plant attractive. Orchid potting medium is sold in better garden centers. A product called Servo is wonderful for potting most types of orchids. It is very easy to work with, much like soil. If you see it offered for sale, by all means buy some.
Nothing is perfect, and orchids do get pests.
If your house is too dry you might find spider mites infesting not only your orchids but other house plants, as well. Mealy bugs are always a potential threat to house plants. They usually come home from the garden center with you. Scale insects are especially insidious. All of these pests suck the life out of your plants, like wee vampires, feeding on the plant s juices.