1. They were divided because of religious beleif, Lower Egypt worshipping Wadjet and Upper Egypt worshipping Nekhebet
2. With the unification, the red crown and the white crown were combined to become the double crown, known as the "Two Mighty Ones"
The crown bore two animal emblems, the Uraeus symbol of the Lower Egyptian goddess Wadjet, and an Egyptian vulture representing the Upper Egyptian goddess Nekhbet.
These were fastened to the front of the Pschent and referred to as the Two Ladies.
The Pschent represented the pharaoh's power over all of unified Egypt
Just as is the case with the Deshret and the Hedjet Crowns, no Pschent has survived. It is known only from statuary, depictions, and inscriptions.
3. The terms relate to the direction of the flow of the Nile, which flows from south to north and empties into the Mediterranean at the delta.
The custom of drawing maps with north at the top and south at the bottom is just a custom. There is no real "up" or "down" to those directions, just orientation on a page.
Ps. do your history homework yourself next time
