RE: How long before seperate puppy from mother dog
From an experience that I had I'd say 7 - 9 weeks is a good time.
My friend bought a puppy from a private person (ie: not a professional breeder) and from the 7th week each new owner could arrange to visit their puppy. She spent time getting to know her puppy as it played with it's siblings and learned how each pup had a disticnt personality. She also spent time alone with her puppy and the mother. This allowed the pup to switch attention from it's mother to her.
Over 2 weeks she visited 4 times and one afternoon she took the puppy with the mother dog and the owner of the mother dog to her home - ie: the pup's new home. The visit lasted about an hour and the puppy was introduced to it's new bed and bowl and had a bit of food in the bowl.
Two days later, my friend took the puppy to her house again - on it's own, for about 2 hours this time. In which she fed it and played with it.
Two days after that she took the puppy home for good - and the pup went straught to its new bed, bowl and toys and didn't cry that evening. The next morning he happily greeted his new family when they came downstairs.
I suppose that is an ideal - but it does give a good indication of a suitable age to separate puppies from their mother and the fun and boiterous activity of their siblings.