I wouldn't say that you are way off base -- being home with a parent is a good place for kids to be according to my understanding of Waldorf. However, the Waldorf parent tot programs, playgroups, preschools and kindergartens emulate the home in important ways. They are very nurturing environments with lots of rhythms and wholesome activities, and lots of PLAY. The kindergartens are also mixed age (4 - 6). With smaller families and lack of kid friendly neighborhoods, Waldorf early childhood education gives kids a chance to learn through imitation and play.
I don't know that anyone can give you a general answer about whether it is difficult to get into a Waldorf school. Some of the more established schools may have long waiting lists; start-up schools may not. It probably also fluctuates from year to year in some cases. (We got on the kindergarten waiting list in Autumn 2000, hoping to start in Autumn 2002. At the time I had heard there was a long waiting list, but now there is no problem.) I would suggest contacting the schools to find out how things are at the ones you are interested in. As far as other admissions criteria, the school we are interested in has an interview process and an initial trial period to determine whether both sides are a good fit.
Hope this helps!