I clean my chain with WD40, and then follow that with a lubrication using tri-flow. In the winter, I do that weekly. In the summer, maybe monthly or longer, depending n conditions.

As far as the freewheel, the rear freewheel needs to be serviced. Depending on the kind of hubs you have, it can be an easy job or a hard job. You can typically find the service manual for your hubs online, and they will tell you how to service the hub. Or you can just take it to your LBS and let them handle it.