If I throw an acid flask or vial of holy water or any other splash damage type weapon, does the Slayer's Studied Target Bonus apply to attack and damage?
Yes, Studied Target applies. From Paizo, emphasis mine:
Alchemist's Fire: You can throw a flask of alchemist's fire as a splash weapon. Treat this attack as a ranged touch attack with a range increment of 10 feet.
Studied Target (Ex): A slayer can study an opponent he can see as a move action. The slayer then gains a +1 bonus on Bluff, Knowledge, Perception, Sense Motive, and Survival checks attempted against that opponent, and a +1 bonus on weapon attack rolls and weapon damage rolls against it.