I think the highlights are also part of the textures in the interface folder, but I'm not 100% sure where they are.
Same for the continent maps, I think you can find the textures in the interface folder.
EDIT: for the continents
Interface/worldmap/Azeroth/
Interface/worldmap/Kalimdor/
contain the textures + highlight for the continent maps
As for the positions of the points of interest, the highlights of each zone, ecc, I think most of them are stored in .dbc files relating to the maps,