Should I separate? How? What is this?

[bil]

Personally unless the mother is in a bad way, I would bin a keiki. They take time to bloom, and with be the same as the mother. So, unless you want several identical orchids...

Re medium. I like coarse bark with all the small stuff sieved out. It can't be over watered. Winter I water them once a week, and in full summer, three times.

If you pot them in moss you have to be very careful indeed. With moss the air spaces fill op when the plant is watered, and the roots slowly start to suffocate. If you water again before the moss has dried out enough to allow air to reach the roots, they will eventually die.

An attractive alternative is to mount the orchid on a piece of aquarium wood, using a pad of sphag moss to retain water. They then pretty well need watering every day in the summer, but feeling the moss is a surefire way to see if it needs water.
Because it dries out fast, this again is fairly rot proof as long a you don't overdo the moss or saturate it everyday in the winter.