The fact that you are a quadruplet should be reported in the special circumstances section of the CSS.
Talking to the financial aid office today or tomorrow at W & M is the right way to go. The FAFSA is delayed this year until March, unfortunately. You need a more definite answer from W & M on aid, and a more definite answer from parents on ability to pay.
With the ED situation, it seems the sooner the better since if you are committed, it would be good to withdraw from other school applications. If W & M is not affordable, you can talk to them about getting out of the commitment and focus on other schools.
You have a good attitude which will make this work out one way or the other.