An hour is way too long. I am lucky if I can do 15 minutes. Don't forget the energy expended in getting to and from class. What seems like an hour to you may actually be 90 minutes or more to the student. I know some instructors like to do warm-ups. For many of us just getting thru the warm-ups would be difficult, forget doing something afterwards!
No standing poses at all. Seated or lying down. Or in a chair. Supported poses with bolsters and such. Soft thick mats. Keep the heart rate down. See our wiki, in particular the section I wrote on pacing.
I wouldn't assume medication. There are no treatments for CFS, anything we take is highly individualized based on the symptoms we are experiencing. Some people might be taking stuff for pain, some people might be on stimulants to stay awake, some people might be taking something to get their blood pressure up. It's a very mixed bag. Some of us take nothing because nothing works.
Warmth is good but some of us are very sensitive to heat and humidity while others are very sensitive to cold, or both. A lot of us are sensitive to light and noise. Music might be nice but it could easily be too loud. Smells are another issue. Incense and scented candles are definitely a no no. A lot of us have what I call "princess and the pea syndrome". Like the princess in the fairy tale we are hypersensitive to everything. Also a lot of people have pain. I know yoga instructors who like to touch you and move you into a correct position. Be careful with this because you can hurt us easily.
I do love visual imagery. I used to take a yoga class where we would do a deep relaxation. The instructor had us imagine lying on a warm beach with a warm soft breeze and gentle sounds of surf breaking and would guide us down into deep relaxation. It was terrific. I also find some of the relaxation techniques in self-hypnosis and NLP helpful.
I learned to meditate decades ago so for me meditation of any kind is very easy. I just do it, wherever, whenever, no matter what is happening around me. I popped a kidney stone the other day and while I was curled up in the fetal position on the floor I found myself counting my breaths to endure the agony. So it has become an automatic response for me.
There is a guy who has had MS for decades and is a yoga instructor. He credits yoga with keeping him going as long as he has. I can't remember his name and a google search indicates yoga has become very mainstream for MS. Some of the techniques there might translate to CFS. Ditto for senior yoga.