A friend's Macbook needs a new power adapter. I don't know the model
number of her unit, but it's white with a 13" screen, and she bought it
at least three years ago.

Question 1: will any "60W Magsafe AC Adapter Battery Charger" (e.g.,
the one below) work with this unit, or are there different voltages etc
that have the same connector but will only function on certain models of

Question 2: In your experience, is it worth the extra ~ $50 to get a
genuine Apple replacement instead of a knockoff?