1. How long does a moisture filter last? 2. Do they come in a top run operation, like in an oiler? Would that run be more efficient?

Thank you for your question. The in-line moisture filter should last years if you take care of it. Depending on use it would need to be cleaned every 3 months. To extend the life of your pneumatic tools you should use the Kobalt 3/8-in Air Filter (item# 221014) off of your compressor and then use the Kobalt In-line moisture filter (item# 495862) just before going into your tool.