I recently created a WCF service (dll) and a service host (exe). I know my WCF service is working correctly since I am able to successfully add the service to WcfTestClient.
I got a more detailed exception when I added it programmatically - AddServiceEndpoint:
string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
ServiceHost host = new ServiceHost(typeof(Service), new Uri(baseAddress));
host.AddServiceEndpoint(typeof(MyNamespace.IService),
new BasicHttpBinding(), baseAddress);
host.Open();