conditional summing

I am trying to determine how to do a conditional sum with conditions such as: if a value is unique, if the value = x, and if the value is the max/min...

I think i struggle with the "if unique" condition the most, i guess i just don't understand how it works.

in any case, i am providing an attachment that *hopefully* describes my objectives a little better.

As always, any help is appreciated. Thanks!

josh