About 30 miles into the trail. Large building with bunks, showers, laundry, etc. The outfitters will help you with pack weight reduction. You can easily resupply out of here. I sent a maildrop here, but you don't have to.

What kind of food to they sell?

Alot of standard hiking fare, like Mac and Cheese, Liptons, ramen, couscous, freeze dried foods, sausage, cheese, jerky, nuts, candy/energy bars, drinks, icecream, some fresh fruit, etc. Not a super market, but very easy to get enough food to get you to your next resupply.

You can also hitch (or arrange shuttle) to Dahlonega (we had to hitch in 3 seperate rides to get to Dahlonega, but it only took 1/2 hour) or Blairsville from here, both have grocery stores for resupply. You can get enough food at the Walasyi-yi to get you to Hiawassee, they have some canned meats, tuna in pouches, fruit, pop tarts, man n cheese and noodles, good candy and junk food selection.

Can I still mail a package to Neels Gap?

As of last year you could. I picked up a package last year about this same time.