does it come with instructions and how long will it last, also is it to use with air guns and nailers

Thank you for your question. The filter does not come with instructions. It can be used with any air tool including a nailer. However, this filter is most frequently used with paint spray guns. The filter has a push-button valve that will allow you to drain water that accumulates during use. How often it needs to be emptied will vary depending on the amount of moisture in the air.