I might suggest New Age music seems to work well. Stick with a program. It takes work. Nothing can replace a good yoga instructor. Tapes and books are wonderful tool for regular practice or when a teacher is not available.
More subdued lighting creates a peaceful atmosphere.
Glad you asked that. Yoga can almost always be used. The subtlest forms of yoga require breathing and the mind, so there really would not be a problem, but the form of yoga should be suited for the person and their problems. Cinda, go ahead. The new age movement is not a religion, but people of more conservative religious backgrounds often think it is and therefore do not try these practices which could help them.