Use Break Free or M-Pro-7 for rust prevention and some quality grease on the slide/frame rails (like Slide Glide or Tetra Grease). Blue Armadillo is also good stuff, but for some odd reason, I have a hard time finding it in our local gunstores. Yeah...its made here in Houston....but most of the major stores don't carry it...odd!
Yes, you need to lightly coat the exterior because SS can rust. Swab the exterior with some Break Free on a rag...then wipe off the excess. Don't over do it. Its not a good idea to run a 1911 on the "wet" side. Some grease on the rails and a drop or two in the hammer, disconnector and trigger is all that is needed. Again...don't overdo it.
For bore cleaning, I use Shooters Choice and JB Bore Compound. A few brone brushes and you're good.
Rem Oil and WD-40 are things to avoid for the most part.
- brickboy240