but how the heck do you find the adjacent faces for each vertex?

Think it otherway round: Iterate over the faces and add to the normal of the vertex. Once you processed all faces, normalize the vertex normal to unit length. I described it in detail here

Calculating normals in a triangle mesh

If you really want to find the faces for a vertex, the naive approach is to perform (linear) search for the vertex in the list of faces. A better approach is to maintain an adjancy list.