Oh my! You threw everything at it except the kitchen sink
Trial and error is a good way of learning things, that's for sure
If you still have a bit of rust you want to remove from the pitting, consider a substance called "naval jelly" or "evapo-rust" (as mentioned above). Just apply it to the area needed, not to the surounding areas. It sometimes does a bit of discoloring itself (typically kinda greyish), but that will be gone when you do the next step (just make sure to follow the instructions that come with it).
Since some of the methods you used may have scratched the surfaces well beyond what Flitz can restore, you may want to try the following.......
You may want to go to your local Home Improvement store (Home Depot or Loews would be fine) and seek out some buffing wheel compound that can be purchased in form of a solid stick. These compounds are used as one would use jewelers rouge and such. You don't need a mechanical buffing wheel, just some good-ole tough cotton cloths. Wrap your index finger with this cloth, then briskly rub the compound stick (working the compound into the cloth). Then buff the area that needs the minor scratch removal and such. What grade of compound coarseness will all depend on the level required to get the job done. One works with this stuff as one would sand a piece of fine furniture before applying it's finish. Example: Lets say you can get the hard work done with 150 grit sandpaper, after that you may choose to follow with 220 grit (smoothing things out a bit, and greatly removing the heavier scratches that the 150 grit left behind). Then you may choose to follow with 320 grit, which will even further achieve the reduction of visable scratches and further work to give an even smoother wood surface.
When you purchase the compounds, you get them almost as you would get sandpaper for a wood furniture project (kinda like.... coarse, less coarse, medium, fine, extra fine).
Flitz is still good, but if one were to look at it in the wood example I just gave, it would translate to one going all the way to something like 1000+ grit in wood sandpaper.
Flitz is really not considered an abrasive at all, though it does work as such, but at an "extremely" low level. A "quality final maintenance polish", is what I consider Flitz to be. What one could choose to maintain and help restore high polishes, but also doubling as an extremely light polish that will remove some very mild scratches and very mild surface rust
