6.54 TLP

For anyone just viewing the page, I am more familiar with Wittgenstein's later work and am curious as to various interpretations of this penultimate proposition of the Tractatus.

6.54     "My porositions serve as elucidations in the following way: anyone who understands me eventually     recognizes them as nonsensical, when he has used them-as steps-to climb up beyond them. (He must so to speak, throw away the ladder after he has climbed up it.)
He must transcend these propositions, and then he will see the world aright."

What is the significance of this passage in its relation to the preceding text?

He is known to have refered to the Tractatus as a treatise in ethics.

I have always seen the Tractatus as drawing the bounds of sense by coloring in a system around it. My discontent with this interpretation lies in this: why not some other system of "nonsense" then?

What reccuring themes are there between the TLP (Tractatus-Logico-Philosophicus) and his later work?
(Other than L.W.'s central ideas about language)

Any reading suggestions as to his intermediary work? I am curious  to find some of his developing positions.