First, welcome to the forum!
This is a great place. And people can/will answer as many questions as you have. Stick around.
But I agree on the pet store thing.
How old is the puppy?
You have a 2 year old and you go to work... so, will someone be able to spend a lot of time with the puppy? I'm not assuming he'll be alone all day, I'm just pointing it out. I have a puppy and a 7 month old and I'm a grad student, so I know it can be done, but you have to plan it out. He will need LOTS of attention.
Don't expect the puppy to use the potty area right away. The first few days when you come home, expect the worst mess you've ever cleaned up in your life. Then, it won't seem so bad when you first see it. lol Most people I have seen use a laundry room or something similar. It doesn't need to be very big, but the puppy should be comfortable. You should leave him some toys, but make sure that they are safe and that he doesn't need supervison while playing with them. Hopefully someone will recommend do's and dont's for toys.
Don't expect the dog to learn to tolerate your son. You really have to expect your son to learn about the dog because you want the dog to grow up healthy and happy, not abused or tortured. It has negative outcomes. Your son will learn to be gentle and he will be fine. Just supervise REALLY carefully! Dogs don't like their hair being pulled or being picked up by the head...
Oh, and don't let him eat catfood. lol He will LOVE it and he will want it if you offer it but it's bad for him. I don't mean to insult your intelligence if some of this seems really obvious... I'm just not sure how much you already know.
And do post pictures as soon as you can! Samoyeds are very pretty...