Sage - I have asked a physics teacher friend about the cooling coffee thing and he has explained it in terms even I can understand.

The rate of heat loss is affected by the differential between the hot coffee and the cooler air. The greater the differential, the more rapid the heat loss.

So, if you buy a cup of coffee at, say, 150 degrees F and walk back to your office through 50 degree air it will lose heat at a rate determined by a 100 degree temperature differential. Then you add cream and sugar and cool it further.

But, if you go ahead and add the cream and sugar when you buy the coffee and cool it to, say, 135 degrees, it will only lose heat at the rate determined by an 85 degree temperature differential.

So, it conserves more heat to cool the coffee before transporting it than afterwards.

Bruce