My recommendation would be to list out your requirements 1 by 1, and start with just one at a time. Upon reading this, I get confused about what requirements come first, and why.
Is your question about filtering to the latest date (a relative date filter can accomplish this; or an LOD expression), or about comparing Regions? Can you mock up some expected results, or further explain the requirements in some more detail? Forum users definitely want to help, but sometimes it becomes difficult to understand the needs of a user with multiple requirements. Thanks!
My primary requirement is to compare the % difference between each region(1 to 1 comparison).
So basically I want to find the difference between the regions.