MongoDB how to do multiple aggregations in one query with C# driver?

My data model looks something like this:

{
    "ListingId": 1,
    "Status": "Current",
    "Category": "Rental"
}

I have around 5 million documents, and would like to run aggregations on both the "status" and "category" fields, so i can produce an output like this:

{
   "Statuses": 
   {
      "Current": 100, // count of all documents with 'Status' = 'Current'
      "Sold": 12 // count of all documents with 'Status' = 'Sold'
      // etc
   },
   "Categories": 
   {
      "Sale": 120,
      "Rental": 12
      // etc
   }
}

Basically, i want to return data to power a 'faceted search' UI, so i need the count's of all facets, and I want to do it in one trip to MongoDB.

I've been reading up about Aggregations and Facets for a day or so now, and i'm still confused.

Questions:

1. Given my scenario and collection size, what should i be using here? Facets or Aggregations?
2. How do i do it in the latest C# driver?

Related questions (which i haven't been able to convert to my situation / code):

• Using Facets in the Aggregation Framework C#
• Using Facets in the Aggregation Framework C# with Multiple Facet, Unwind and sortByCount