I think you should tell your brother to wait until the female is atleast 2 years of age --- so maybe next fall instead of next spring. I believe that 28 months is the ideal, though I'm not sure. My breeder never breeds a dog unless they are over 28 months of age. Boxers often need C-sections -- if the female is bred too young, her pelvic bones won't be completely developed. Tell your brother he's looking at a $500-1000 C-section.
Giselle is right, only flashy boxers bred together will create whites. All flashies carry the white gene and will have 25% white pups in a litter together. If the dogs are both solid fawns, they will only produce fawns.
It's highly doubtful the puppies will be show quality. You might get one show quality puppy in the entire litter. There are some breeds where almost every dog from that breed is show quality -- boxers are most definatly NOT one of them. It's extremely hard to get a show quality boxer, and they are a very common breed.
