[Stiglr]

Hear, hear for the selectable/editable rotation point!!!!

As for the "insert vertices", what I do is complete the Insert Vertice operation, then, with my ortho view in Wireframe (w toggles it) use Move/Size. I grab the new vertice, and deselecting the ones on either side of it. While I do this, I can see all three vertices, and the line between the three before I deselect. A little wiggling around will quickly show you which line you're moving along. Then, after undoing the move, so you're sure not to misplace anything, it's pretty simple to move the new vertice along the line shared by the original three vertices: as long as you stay along that line, the line itself will not move.

Hope that makes some sense.