the cocoa butter in chocolate consists of many fat groups with melting points
that vary between approximately 60 and 110 degrees F. Cocoa butter actually
melts a few degrees below this but we warm it slightly higher to make sure. The
fats that melt at the higher temp. are also the first ones to solidify as the
melted chocolate is cools. These fats, when distributed throughout, are what
give the chocolate its gloss and solidity.(if properly tempered the chocolate
should break with a snap).
FOR DARK CHOCOLATE
melt and heat to 115-120
cool to80-82
warm slowly to87-90
FOR MILK OR WHITE CHOCOLATE
Melt and heat to 110-115
cool to 78-80
warm slowly to85-87

The reason why you reheat it the final time is because when you cool it down
the chocolate is now too thick to use and must be warmed before it can be
utilized. Great care must betaken in this final step. if you let the chocolate
get just a few degrees above the recommended temp, too much fat will melt and
the chocolate will separate and show on the surface in the whitish pattern
known as bloom.

hopefully that answers some of your questions. i have been following those
temps i posted above and have gotten good results. good luck
Mike