Good Morning, (not in the order of your questions)

1. What's your CYA level? might be the cause of excess Cl usage. Alk and salt readings are fine

2. Acid addition will never stop....it's the nature of SWG's. Your quantity seems normal.

3. You'll need to shock with Clorox or Cal Hypo....but tell us your CYA reading first.

4. Not unusual at all not to add salt....maybe most of the Summer