I used notepad ++ because it's easy to search through a large amount of text, but you could use windows notepad if you had the patience. In native, each of the 16 companions is assigned a number, and I believe the simple triggers file is what causes the companions to like or dislike each other. The easiest way to convert from Calradian characters to new ones, then, is just to rename and reequip them. In gameplay, I've found that the converted native characters do have the same likes and dislikes, so the real mystery is what the new ones like or dislike.
The race does not factor in at all. Not one bit. But, if you wanted to roleplay an Angle-hating Briton, you may not want an Angle in your party. That's all, nothing more. A few characters don't have a well defined race, anyway.