Labels for wires / ensuring text stays on top of wires?

What version are you using? I could not managed to put text labels on top of wires in 1.0.3.
I think this is a bug in Fritzing and you may report it in the bug tracker. It seems that logo items (letx elements) are treated as regular parts, when it should treated as labels. You can activate the layer pane (Windows->layers) and disable enable the different layers. In Fritzing, the breadboard elements are at the bottom, then the parts, then the wires and then the labels.