@Rozy
I noticed with your files you had none set for the male gender. This means with every male gender of your species it has to go back and use the default portrait. If that was not what you were talking about can you please give me an example?
@Baalshazar
Unfortunately these instructions were made with photoshop in mind. I have used photoshop for so long now that when I tried Gimp I found it extremely confusing. So in this respect I can't really help you. instruction 5 just means to have what you want the players to see already cut out, it depends on the image your using and how much of it you want the players to see. There should be a way to turn the visibility of the alpha channel off.
I can't help you with the .dds save either, you will just need to test until you get a working one. The most important part of the DDS save is the first line.
Also, if you send me your .dds file, I can look it over and get it done for you and send it back. This way you might be able to see how it should look in the end.