Yes, the therapist can still offer certain massage techniques where the client can be fully or partially clothed.
No, this would be a breach of the clients privacy conditions.
Sports remedial massage can be slightly sore due to the therapist going deeper into the muscles, if the client is getting a relaxing massage this will be soothing and no discomfort involved.
Times will vary depending on the massage treatment.
Should you fall asleep the therapist will wake you in a soft and relaxed manner.
Yes this is very normal as you are in an extremely relaxed state.
This is a choice that can be made by the client. Your therapist is there on hand to offer advice should you need it.