Call Customer Service at their 800 number. I talked to them a while back and at that time the next available appointment was 24 October. We plan on being there the end of the month and will do the standby thing.
We have done it in the past and the wait wasn't that long.
As for an address: Plug in 605 W. Crystal Lake road, however, once you come of State Hiway 9 and turn left at the Winnebago dealership, follow the road for about two miles, you will see the visitor center on your right. Make a right turn at the intersection, another quick right and go about 1/4 mile and Customer Service will on your left.
Really easy to find. Also, on Thursday, the Lodge has an "all you can eat fish dinner." We recommend it, as I am sure others will also.
Enjoy your stay.