Didn't you just answer your own question?
I thought it was the same as developers: 20%.
Didn't you just answer your own question?
25% is once per calendar year.
Except that they don't track how many 25% discounts you get. I used to use my 25% discount for multiple machines a year, a lot of people in my store did, and nobody really cared. Also, you get 50% off software as well as well as free copies of OSes, iLife, and iWork suites.