Summary
In this tutorial, I will try to explain all options available when modeling in the edge sub-object.
Under this you can see all the options you have in the ESO.
Selection
Shrink: Shrinks your selection, just as in the VSO but now applying to edges.
Grow: Grows your selection, just as in the VSO but now applying to edges.
Ring and Loop: Ring and Loop are very similar. They make selections easy. Ring does it perpendicularly and Loop parallel to the edges' direction. To see what Ring does I selected one edge, then pressed Ring:
On the other hand if I would select a different edge and pressed Loop I would get this selection:
This obviously also works with more complicated meshes and shapes and is therefore a very usefull tool when making complex selections in a fast easy way.
Edit Edges
Remove: Removes an edge you select. Works a little subteler than hard deleting it, in that it rebuilds the polygon from which you deleted it.
Split: A sort of detaching, utterly useless.
Insert Vertex: Don't use that here, use 'Cut' in the PSO.
Weld: Welding Edges? Yeah right. Do not use this. Looks like nonsense to me.
Extrude: Creates a sort of spike, so very usefull if you want to make a spike, or when selecting a whole Loop it could be used the create an outward seam for instance.
Target Weld: I think they forgot to turn this button off. It doesn't do anything for me.
Chamfer: THE tool for giving your model the right shape when you're modeling with the help of MeshSmooth. This tool will be extensively used in all further tutorials, 5-9. It splits an edge into two and thereby creates a new polygon. Can be set either manually or 'by the numbers'. Last one is preferable if you want a consistent model.
Connect: Connects edges, by creating new ones from the middle of one edge to the other. Also works on a larger selection. For an example between two edges see the image below:
More 3D Graphics: 
