3) I don't have a Tortoise manual in front of me (it explains all this, with diagrams), but one of the contacts is the "sliding" contact and the other two are the "stationary" contacts. The "sliding" contact will connect to one or the other of the "stationary" contacts depending on the position of the Tortoise, but the two "stationary" contacts will never come in contact with each other.
How you'd wire those depends on exactly what you want to accomplish. If you want a single power source to power one of two loads depending on the Tortoise's position, you'd connect that source to the "sliding" contact and each of your two loads to their respective "stationary" contact.
On the other hand, if you want either a positive or negative source to a single load, you'd attach those positive and negative sources to the "stationary" contacts, and your load to the "sliding" contact.