Any clue where to get at night or early morning? Are there 24 hour places??
When my flight was seriously delayed last summer, the only things that were open in the wee hours of the morning were a couple of Starbucks.
Other than MAYBE the previously mentioned Starbucks near baggage claim, I don't think you'll find any 24 hour places in the airport at all. The airport tends to get quite dead from about midnight to 5 AM. After 5 AM, it's more American breakfast fare until the lunch hour. For lunch you might find a crab cake, but I don't know of any place in any of the terminals that's like to have whole crab.
If you're prepared to leave the airport, things aren't much better -- Northern Virginia is a notoriously sleepy place after midnight or so. The only proper 24 hour one I can think of, which will come with a ~$30-40 round trip cab ride including tips, is the Amphora diner in Herndon (http://amphoragroup.com/about-us/locations/). Their menu has crab cakes -- and I'll bet they're tasty -- but again, unlikely to have whole crab.