When we took the tour a few years ago there was no charge and you weren't required to be a guest of the WL. You just showed up for the tour, with no reservations. It started at a place near guest services in the lobby. You might ask guest services to make sure you are in the right area to start. If I'm not mistaken the afternoon tour has been cancelled, but you might check with guest services.
When we inquired a few weeks ago while there, you just showed up at the right time in the lobby for the morning tour - it was listed on the activity sheet they have each week, too. There was no need for advance reservations. If you aren't staying at WL and want to tour, you can just call from your hotel to ensure they are offering it the day you want to go.
They were not doing the food one, just the morning Lodge tour, when we went and they said the later one has been canceled...
The tour now consists of the lobby and going to the 4th floor for Ranger Stan(or another Ranger) to explain about the floor pattern and tell about other interesting items. A few years ago, the tour also included going outside to see the pool area and some of the landscaping. The tour was between 45 minutes and an hour long then.