To select the edge of a smesh, hold down the Shift key and click on that edge. The selected edge will be highlighted. You can select as many edges as you want while holding the Shift key, and you can deselect as well. There is no way to select multiple edges with a fence, only direct selection is available. When you select an edge both nodes associated with that edge will become selected.

Ignore Back facing

Selecting the Ignore Back facing option will limit the selection face, nodes, and edges to those on the side of the object facing the user.