Making my home use less energy

I have a house that is about the size of Al Gore's.  I know he has been getting a lot of grief about how much energy he uses.  Recently he apparently upgraded a lot of systems to "Walk the Talk".  I have looked on the web to see what he has done, but really can't seem to get any really good information.  Maybe I can provide some answers by doing things to my own home though, that others might benefit.

I am in the planning phase for my energy conservation project.  I want it to:

• Save energy
• Ease maintenance
• Have a near term payback
• Be resilient to future upgrades and technology

My general plan is to:

1. Implement a monitoring solution so I can measure performance
2. Switch to geothermal
3. Consider solar thermal and electric
4. Improve insulation and windows
5. Increase automation/conservation

My house is large enough to almost be a commercial property, but small enough not to be - so there are a lot of complexities to how best to balance out my systems, recover energy, etc.  Some of these questions include.....

1. Should I replace my 5 5-ton AC units with a single chilled water plant?
2. If I replace my 5 air handlers with geothermal, should I still use my boiler to supplement heat, or use electric re-heat coils as often recommended by HVAC vendor
3. Geothermal has a slow "Recovery Phase" (that means if you set back your thermostat in the winter, the system can produce enough peak heat in the morning to get back to proper temperature in time for breakfast).  So, does the improved efficiency of geothermal make up for a setback strategy - what is the payback?
4. I can fit a lot of solar thermal on my east facing roof.  Not a perfect direction, but is it worth augmenting my system with some of that heat?
5. I need more insulation in my attic.  I have 2 air handlers and my second floor ducts in that space.  Should I instead insulate the underside of the roof?  What is the real science behind vented and un-vented roofs?
6. If I super insulate the attic, how much tonnage reduction will I have, and how will that effect cycling of my Geothermal system.  If my load is 25 tons during the summer now, and it goes to lets say 20 tons with super insulation, will those larger units cycle excessively?
7. I get most of my energy from Coal (the power plant).  Natural gas is going up in cost.  New power plants will have more natural gas.  There is a high loss rate in electricity distribution, so with increased energy cost will I be better positioned to heat with natural gas or electric (via heat pump)?  What is the cross over point in the business case for this?

If anyone has answers or thoughts please comment.....