I implemented the functionality, that you can pan and zoom the whole graph but also being able to drag one specific node. My problem at this point is, that I can't find a way how to update the edges while dragging a node.
Here you can find a minimal setup:
http://codepen.io/anon/pen/XJZrxm
In:
function dragstarted(d) {
// find edges which link to the currently moved node
}
function dragged(d) {
// update edges
}
Of course this behavior should also work with much more nodes and edges.