Answer: Yes and yes
Goto war3viewer and find the blp files for the scorescreen background. Extract, alter, save and upload it into your map under the same file path used in the viewer (ie.e ``textures/glues/scoresceen/bottomleft`` or whatever it is). Hope this helps.
The stat background consists of four files (one for each corner), and theres 5 seperate files for each of the race stat pics (NE,Orc,Human,Undead and generic defeated) Thereis also sperate .blp files for the tabs (i.e. units, rescourses, heroes, ect.)
-VGsatomi