If I am building a magus hexcrafter and I choose prehensile hair as a hex, this gives me an intelligence bonus the same as if it were strength. So say I have 20 INT. I have +5 to hot and +5 damage. This weapon is 10 feet reach
If I take White Haired Witch, I am automatically granted a five foot prehensile hair attack with my INT bonus used for damage.
If I do a prehensile hair attack, am I choosing one prehensile hair attack over the other or are they combined. Can I add my regular bonus of +5 to hit to my white hair prehensile hair attack and use that bonus for grappling or tripping?
The White Haired Witch 'White Hair' Class Feature is not the same as the Prehensile Hair Hex. The wording has a number of very specific differences. Not least of which, right out of the gate, is the fact that 'White Hair' is a primary natural attack & Prehensile Hair is s secondary natural attack.
On the bright side, this does mean you get your total BAB with White Hair attacks, including the Maneuver actions.
On the other hand, there are a number of factors regarding White Hair that are either unclear or rule unfavorably.