In my opinion, I'd go with what the application says. I'm assuming that the website it giving more general information which may apply to more than one program, hence the 2-4 approximation. The actual application is what you need to follow and if it says 1000 words stick with that.
Regarding word limit: When I went to an info session for my program, what they said is that you really need to stick to the word limit. They said that it shows them that you can both follow instructions and say what you need to say very succinctly, which are clearly important in grad school.
Edit: I thought that each double-spaced page (12 font) is about 250 words. That would make 4 pgs approx. 1000 words, give or take.
