As for submitting your prep, Look at Important Prep Links. Third one down says Log assignments on the Entry Form. (Opens Oct 1st)
The last Link is for Entry into Contest Rounds: Compete in the "October NaNoWriMo Prep Contest Rounds"

You can do what some of us past preppers do and make a folder in your Port to save your work. I also copy the Prep Calendar.

As for the important instructions: All (Which is why I usually copy those to.)

We are here to help you and cheer you on.