You will find that in some seasons and heavier use your pool will require water more often. You can have a automatic water level maintainance put in but during cooler monthes you'll add none. If the water gets below the intake you can burn up your pump. watch you level.
The water should contain chlorine in order to kill germs. You won't know who or what might land in your pool.
Add salt
You add water to the pool
Remove some water in container (10-20%) and add new water. example: pump water high in cyanuric acid out of a swimming pool and the add fresh water to the pool.
Normally, about once per week. Possibly, up to 2" to 3". K
Yes, you should run the pump when you add chemicals to your water,
If it's cured sufficiently to add water, it should be cured enough to use.
I should add, no chlorine in water.
You need to replace the water that evaporates.
Reduces alkalinity of swimming pool water (softens hard water)
The length of time between pool shocks varies. It depends on factors such as how often the pool is used, how many people use the pool and other factors. It is best to have a test kit to check the chlorine level and the pH balance to decide how often to add chlorine or to shock the pool.
Drinking water? Of course not! For the purification of the pool, maybe. That's why people who swim too much get red eyes...