Use a plastic credit card to spread the wax and clean the spaces where you don't need it and use denatured alcohol, instead of sanding, for removing the excess wax.
I'm not an expert in this by any means - I found a page that dated movement pillars and that seems to agree with your assessment. Several other pages have said that Peter Wise was active as a master clockmaker from 1725-1741. I will say that I have several other bell strike clocks including one not too much newer, and this movement is noticeably nicer.
Re-waxing the numerals and silvering are unrelated processes (though it might be difficult to wax without also resilvering). If you are happy with what your numerals look like, yes, you can absolutely skip the waxing and go right to sanding and silvering.
I don't have any information on this, sorry. The silverers I have followed use silver chloride. My high school chemistry causes me to think that the end result of exchanging the copper for silver is exactly the same, even if the process is slightly different.
Coincidentally I stumbled across this post that answers your question: mb.nawcc.org/threads/re-silvering-a-1913-junghans-bracket-clock-face.187124/post-1529128 Silver chloride is required for the silvering reaction. Silver nitrate is a mislabeling of the active chemical, but is apparently what is on the bottle of several silvering products.
