Hotels and alternatives
Nothing. You'll have to camp out in Sidi Ali el Mekki (about 4 km) or travel the about 60 km (either direction) to Tunis or Bizerte if you want a hotel room for the night.
Restaurants and alternatives
Simple eateries in the town centre.
Nothing. Go to Tunis or Bizerte to get full bank and exchange services.
There are infrequent bus connections between the main road and Ghar el Melh. In summer these are more reliable, as many people come out here (and to nearby Sidi Ali el Mekki) for day trips.