The red lines in Jake's drawing are new wires/lines used to support the spin pole. They originate from the same eyes on the hulls, but do not attach to the forestay. Don't move the bridle wires for structural reasons.
Exactly. If you extend the pole much farther than you already have it mounted below the furler, the middle of the pole will start to swing side to side as the spinnaker pulls the pole sideways. These baby bridles help keep the middle of the pole centered. They will also help the pole survive if you pitchpole with the spinnaker up. If the bottom of the spinnaker enters a wave it will push the pole rearward and the middle will flex up and snap.