This sounds like a problem for the Windows Azure Management Libraries. A c# library that microsoft is releasing soon. You can get it from Nuget as prerelease at this point.
Microsoft.WindowsAzure.Management.ServiceBus
and heres some code that will get you started.
using (var azure = new ServiceBusManagementClient(...))
{
var allYourServiceNamespaces = await azure.Namespaces.ListAsync();
var topic = azure.Topics.Get(allYourServiceNamespaces.First().Name,"topicname").Topic;
}
I am not sure if you can get the processing time per message ect, but it can give you the same information you can get from the REST API.