Letters of support are due on the application deadline. As soon as you fill in the contact information for your letter writers, the system will send a message to them containing complete instructions on how to submit a letter on your behalf. You may want to fill in this section before completing the rest of the application in order to give your letter writers ample time to compose and submit their letters.

No, the proposal will not be available to the letter writers at that time. The best approach is to send them a copy of your statement or otherwise discuss the project with them ahead of the deadline.