The right elbow should move back and through on 'its' plane. Extensor action should be your goal, 'letting' the elbow bend is good, but trying to 'tuck' the elbow in, or holding against your side isn't (unless you are able to maintain your radius and center with a steep shoulder turn).
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Yes, and you can "move the right elbow back and through on "its" plane" by lifting on the BS and "dropping it back" on plane, OR simply letting it fold (and as I said, it would still move up, but not by much) and unfold (you can do this without tucking it or pinning it to your side).
You get a flatter plane with the ladder and I believe its "theoretically" more effecient since you dont have as big of a gap to cover to get it back on plane on the forward swing (Nicklaus had to REALLY drop the elbow to get it back on plane, Hogan did not).