Self Sustained living

I would like to discuss the merits, needs, and requirements of what would be nessesesary for an off the Grid type living situaition. The main idea being that to be prepared for a WTSHTF scenerio you would already be prepared because yourself and family would already be living independantly.

How much land would be required?
What kinds and how many livestock?
Gardening and orchard requirements?
What skills would need to be mastered?