Implementing custom IRenderer for ArcGis 10.0/WPF

EDIT: Updates in the bottom

As a followup to my earlier question, I'm trying to implement custom symbol rendering for my WPF/ArcGIS application.

I'm accessing layers that have been published on the ArcGIS server, with pre-existing symbology already in place. I want to keep this symbol, and add text to it, since FeatureLayers don't automatically display their data labels. I'm running into several problems.

I've defined my renderer thus:

public class EntityLabelRenderer : IRenderer
{
    public Symbol GetSymbol(Graphic graphic)
    {
        var objectId = graphic.Attributes["OBJECTID"]; // always set.
        var graphicFromServer = //Use a QueryTask to fetch the object;

        return graphicFromServer.Symbol; //add text
    }
}

When I load my layer, GetSymbol is called for each object, but the Graphic object I get in the call is very barebones - the Symbol property is null, and the only values I can get are the ID. So I use that ID, as I show above, to fetch the full Graphics object with all its properties using a QueryTask. But even the one I get now has its Symbol set to null. Additionally, I don't know what the default data label for this object is, as set on the server. I have all the fields, but have to decide myself which to display.

So my question is: 1) Can I get, for a Graphic object fetched from an ArcGIS server, the default data label as defined in the MXD? 2) Get I get the default symbol for an object, as defined in the MXD on the server? Can I get that, then create a composite symbol comprised of both that symbol and an additional TextSymbol?

3) Is there another, better way? The only one I could think of was to create a custom GraphicsLayer and add TextSymbols to it manually for each object of mine, but this seems insanely complicated.

----- Update -----

I've gone over this and tried some things, and here's where I am in my attempts to get this working:

If I wait until my FeatureLayer's Initialized event is fired, I see that the layer comes populated with an IRenderer for the server-configured symbols. This is great, since I now have the symbol I want to display, as well as the layer's definition of the default text (to display as a label).

So now I can create my own IRenderer which wraps this server-generated IRenderer (usually a UniqueValueRenderer or UniqueMultipleValueRenderer) and adds the label. I can see two approaches: 1) Hacking into the existing renderer, changing its ControlTemplate to add my label, or 2) Somehow returning a composite Symbol that contains both the existing Symbol and my own TextSymbol.

Option #2 is better, but it seems that unlike the Flex and Java SDKs, the WPF SDK doesn't have a CompositeSymbol object. I'd rather not go for option #1 before I'm sure that a CompositeSymbol can't be implemented somehow. Does anyone know how I can go about this?