pdq,

Hmmm, surprisingly no responses even after 22 people looked at your question.

I will take a small stab at this one but I am sure JeffB, Len, Black Frog or one of the others can fill in the blank spots.

SE/PDF stands for Stored Energy divided by either Peak Draw force or Pounds of Draw force...I forget which one though.

My memory on virtual mass is even fuzzier, but I believe it has something to do with the way any given bow releases its energy into arrows of different mass weights.....but I think I am way off on that one. I do seem to remember that the higher the virtual mass the "better" the bow is in terms of transferring energy.

If anyone has one of the older copies of Bowhunting World laying around then Norb goes into a specific description of all of that info....

Sorry I couldn't help more.