At that age I usually five 50/50 kitten milk replacement and soy baby formula. I go half and half because kitten milk replacement has a lot of Taurine and soy makes it easier on the rat stomachs. Lab blocks or the non-medicated hog feed soaked in the mixture would be suitable for feeding.
Rats do best in trios. Duos are okay if they get along but can turn horrible quickly if the two do not like one another. The third adds a mediator and generally makes for a happier colony setting.
I can't really tell on the color, but it appears to be a blue, possibly a variant of blue diluted with a different color. What are the colors of the parents? Looks like some weird blue and AM mink combination but it may just be the lens color of your photos.
Congratulations on your new pet!