Exposure correction Question

Hi, i have been using C1LE for a little bit now, and have a few basic questions -

1. Whats the difference b/w correcting for exposures via EC to using the "Magic Wand". More detailed question - EC is quite obvious - equavalent to using your EC dials on the camera, but the Magic Wand, reduces the histogram values and eliminates all levels that are not used in the scene. Example, if your scene has tonal definition of 40-130; the Magic wand, positions the triangles to 40, 1.0 and 130. Using the EC slider on the other hand, moves the scene histograms and possibly expand it to fit the entire 0 to 255 range. My question is - which is better?

2. What are your typical Exposure Warning settings? I use 0 and 255 for Exposure warnings - and hate the red and greens all over - sometimes it just doesnt make sense.

3. What are your sharpness settings? I use 74 and 3 - and found it reasonbly ok - not great but generally ok.

4. Do you store your exposure, WB settings? do you use custom curves? are there anyplace on the internet i can find these curves?

Thanks in advance for your answers!