You have a multi-part question.
A quick way to compare one period to another is to make a duplicate of your data source. In the copy, create a calc where you add 13 weeks to the date field:
DATEADD('week', 13, [Date Field]).
(or you can do DATEADD('month',3,[Date Field]).)
Then you blend the original data source (primary source) to the copy using the original date field in the primary and the calc field in the secondary.
This will connect the older data to the current data, and you can easily compare SUM([whatever]) to SUM([duplicate source].[whatever])
Now you have your comparison.
Part 2: Create a calc that determines the difference between the two values. The calc can set a value of 1, 0, -1 if up, equal, down. Or "Up", Same", "Down". Whatever. You put that calc on the color shelf, and set your colors accordingly.
is there another options? this method is slightly impractical because my data source is enormous.