Cornerstone 5 Plus Herbicide is a non-selective herbicide, so it's applied when weeds are actively growing. Depending on how difficult/established the weeds are, you can use it at a rate of 0.6 oz to 13 oz per gallon of water.
Cornerstone has a screw off cap. It may take a bit more strength to unscrew the carp if it was overtightened.
Cornerstone 5 Plus Herbicide is a non selective product meaning it will kill whatever it is sprayed on, so no we would not use this product on the lawn unless you plan to reseed those areas.