You might want to re-post over in the Google For Nonprofits Help forum as there are several over there that are extremely knowledgeable about Google Apps. Most notably Simon. 

Also, if you haven't done so already, be sure to look into the Google For Nonprofits program (www.google.com/nonprofits) as you org would likely be better served through that program instead of the Google For Education account. 

Plus, it could qualify you for the Google Grant which is up to $10,000 per month in free Google AdWords advertising. Which is what we specialize in on this help forum. 

All the best,

Robert