The Bethel Woods Center for the Arts says, at its website, that it is located "(a)t the site of the 1969 Woodstock festival." If that information is correct then I'd guess that the farm's address...
Max Yasgur's farm was in Bethel, New York.
It can be any size, from 10 acres to over 1000 acres.
The average dairy farm in the United States as of 2007 had 144 cows.
Westside, Jacksonville 100 acres