age your water for a couple of days (run an air-stone in a separate container of water that you are going to use for a water change)
yes use the water ager/conditioner you have been
This will be sure to properly remove chlorine from water.
Keep your ph level to the desired level with your fish type.
Putting in proper amount of aquarium salt should help with fin healing.
Use stronger treatments like Melafix if needed?