how would I do that?
Programming a game (2D, 3D or otherwise) in D3D11 is a bit more than can be (or should be) explained in a topic. Googling for tutorials or game engines which implement 2D using D3D11 would be a good place to start.
Would I simply map textures onto primitives and fix the camera(view/projection)?
Pretty much. Most 2D games use a single angle of view and (commonly) an orthographic projection. As mentioned, you'll have to decide if you're coding for a side-scroller, a top-down, a 3/4 view, etc., before you start. Getting some experience with 2D rendering in a scratch project will benefit you a lot.
What about a "hybrid model" where it's the same as the above but somehow to take advantage of 3D models
As mentioned, you can use 3d models for your animated characters, but animating/rendering may be simpler and more efficient with images of various character orientations, versus modeling various poses or animations for a 3d model. True, you wouldn't have to re-capture images if you modify your 3d models, but you'll have to decide if your game is for your convenience while you create it or for the end product.
Edited by Buckeye, 06 June 2014 - 01:39 PM.