I agree with everything Hersute said. I think his outline for a partial is perfect. He's absolutely right about sending in a hair sample. The factory won't just match the color of the hair, they'll match the thickness of the actual hair itself as well. This is really important in getting a good blend. I think freestyle vent is probably the way to go. Ventilation is also very important in getting a good blend. If your natural growing hair grows one direction and the piece is vented in a different direction then it will be quite obvious that something is amiss. With as light as your hair is, visible knots shouldn't be much of a problem at all. For a piece this small I would definitely go with single knotting through out the entire piece.