Mine is right at the top line of the tile after about 5-6" of rain in the last week. DH and I were debating a drain - if we get another soaker today - I am draining about 2" out.

Yes you will need to add more salt if you have to drain and your salt level is low - my pool builder says that the warning light is just that - a warning. But if you drain it the salt concentration will not increase - just add about 1/2 as much as you think you will need and then test and see if you need more.