RE: Started or pup
First, a house dog can be a good hunting dog. My dog is a house dog(completely spoiled) and he is a great hunting dog.
Second,
get a pup. Half of the fun is training him and watching the results. A GSP is a great dog. That is what I have. Don't be worried about not being able to train him. They are very trainable dogs and if I could do it so could you. Alot ofthe learning curve for a hunting dog comes from instinct. You just have to sometimes point themin the right direction.
Good luck!