Try Whink Rust Remover on the faucet mesh Louie. It should help you get most or all of the rust off. But if the metal is rusted thorough it may also break off too.
I think your idea of providing extra support by bracing the back of the sink where its cracked is well advised. I’m impressed with your attention to detail and the progress you’re making. Keep up the good work, it will be worth it in the end.
This O ring has proven to be difficult to find. The owner of DEA was very helpful. He told me the valves on my Crane are most likely from another brand, not original Crane, hence the issue finding the correct ring. Nevertheless he recommended Rectorseal pipe thread sealant and it would work just fine.