2. You should have most of the wiring you'll need to get a 12pin plug from an SX (or another brown 10 pin and adapt) and re-pin all plugs, extend some wires and re-pin them... There are various guides over at twincam.org, just seach for cluster in the FAQ section. You may or may not need to modify the tacho electricals in the SX dash to work with the Gze... again FAQ or one of the forums at twincam.org has a document detailing howto accomplish this.
3. If you have an AE101 it will be an electrical sender, an AE92 box will have a mechanical sender. It is located on the firewall side of the gearbox, below the shifter cables... almost below where they are held onto the gearbox by the clips... just a bit closer to the engine.