Sounds pretty good.

Getting the salt up, so the SWCG will generate, would be my first step. The one bag is a good place to have started! Please be careful when adding either the salt or the cya!

How long had the pool been running before you tested? I wouldn't trust the salt and cya before the pump ran 24 hours. It's far better to go slowly (smaller additions of the chems), and see how things progress.

As for your brown stains, they are probably organic and will lift when your chlorine level comes up. If you want to speed up the lifting, we can tell you how.

Have a great pool season!