1. My favourite definition for time is "wibbly, wobbly, timey, whimey, ball of stuff", but that doesn't really say anything :-) Time is the fourth dimension, which is relations of events. Three other dimensions are relations of distances in three different direction.

2. I can't really tell. Noclevername said that energy must exist (energy and matter being the same thing, so...) but I'm not sure about that either. What is needed, is an event or events. I our universe, energy is nesessary for something to happen, so I guess it's needed. One might say that event's like expansion of space doesn't need or have energy (exeption being the acceleration of expanding), since it's an event of space.