I completely agree with the above posters. If the breeder won't keep him until 12 weeks then you can find a much more reputable breeder. Puppies learn a great deal from their mothers in the 6-12 week age range and a lot of negative behaviors can result if they are taken from their mothers too young. Many people on here could steer you in the direction of a good breeder. I know you are very excited about getting him in 3 weeks but it's really not worth it to have a potentially sick puppy with behavior issues simply because the breeder didn't do what was right for the puppy.
As far as shampoo I use EarthBath Puppy. A lot of people on here use MinkSheen and really love it.
Food-wise I feed Acana and haven't been happier with any food. I LOVE it and so do the pups.
Good luck with everything!