Refurburbishing alloys is a thankless task, and to be honest it’s one of these things best left to the professionals and powder coating, rebalance, etc. That’s different if it was just a scuff, but this is a full strip-down.
The time, cost of materials, including zinc etch primer, base coat primer, colour coat and a few coats of lacquer soon mounts up.
If you’re determined to do it, then the alloys need to be spotless. Paint wise, then Würth silver metallic is as close to Audi OE as you’ll get.