Very good !
There is one part which I didn't find out yet, it is the bootsplash in the Live, the one which hides the messages from kernel. If I rely on the grep I did in the "isolinux" directory, there is an image inserted in the file "init", and I don't know yet how to create or to modify this one. I have asked someone by mail, I hope to get an answer within a few days. I think I will be able to provide the size required for images for the other parts.