I do not see its primary purpose being training the elbow, or strengthening any muscles. There should be very little tension involved. Therefore it wouldn't strengthen any muscles.
If the elbow is held in the correct position (an unnatural one) then muscles must be involved in keeping it there. If the arm is moving, however slowly, then muscles are moving it. Therefore the first section of SNT trains the musculature, as well as joint and tendon flexibility, in functioning from a position which is not natural for human beings. It is done slowly and repeated a lot because of the unnatural nature of the position, and the need to train the body for it in a thorough and repeated way.
Going this slowly you are also not specifically thinking about any elbow position or anything else.
I would disagree. During this section of SNT it is important to think of the elbow all of the time, because training the elbow is the end goal. I don't think that meditation is as important as the elbow in VT.