To solve 1) - 3) you need to have a good knowledge of a 3D modelling tool (Blender, Maya, SoftImage, etc.):
You need to learn the basics of modelling and animation. Then you need to learn how to export models and animations from the 3D modelling tool into a format which is supported by XNA.
On the coding side: You need to learn how to import models and animations in XNA and how to render models and playback animations at runtime. XNA and our engine supports loading of models and animations. In some cases you will want to extend the existing mechanisms (e.g. the XNA content pipeline) or create your own solutions.
Once our engine and our Game Editor are complete, things will be easier. But until that point a lot of coding on your part is required to create a full game.
1) If you want to make a terrain quickly, I recommend you create a terrain model in a 3D modelling tool. You could also download/buy an island model on the web. But in most cases you will still need to adjust the model in 3D modelling tool before it can be used in a game.
2) To do facial animation, you need to first learn how to create skeletal animations and/or blend shape animations in your 3D modelling tool. In the modelling tool you can create the complete animation (e.g. the complete dialog). Then you need to find a way to export the animations, so that they can be loaded at runtime. XNA and DigitalRune Animation support skeletal animations - but there is still a lot of coding required to make this work. Blend shape animations, most commonly used for facial animations, are also possible, but require even more coding and understanding of meshes in XNA.
3) I would model or buy a chair model, then load both the chair and the Dude model in the 3D modelling tool. In the tool you can create the required animations. Then, again, you export the animation and play it back in XNA.
4) You do not need to wait for DigitalRune Graphics to render a light source and a model. Using XNA you can render a model using the Model class and the BasicEffect. Using the BasicEffect you can set the sun light as a DirectionalLight.
In DigitalRune Graphics things will be alot easier: You will be able to define a camera object, light sources, models, and the graphics engine will automatically render the scene.
If you want to do everything on your own, you basically need to be modeller, animator, and coder. These are a lot of roles to fill. But that's the life of a hobby or indie developer. ;-)
But game development can be learned step by step; and you can create meaningful experiences without the advanced stuff (like facial animation).
Note: I'd be wary about the 3D resources link you provided. The description of the Super-Man model says "Superman from 'Mortal Kombat vs. DC Universe'.". I doubt that you can legally use a model from another game. I recommend sites such as http://www.turbosquid.com/, which provide clear license terms.