<< 1) The core philosophical texts of 'Determinism' are ... ? >>
Jesus, it's been a long time since I thought of this stuff. In early modern philosophy there is de la Mettrie's Man a Machine; Hume discusses the compatibilist line. Kant's practical philosophy is a prolonged attempt to wriggle out from under the implications of hard determinism. In modern times, John Hospers wrote a detense of hard determinism, as has, more recently, Ted Honderich (called, I think, determinism).
There's a classic collection, now rather old, Free Will and Determinism, ed. Bernard Berofsky (Harper 1966): Sidney Hook has an anthology from the same vintage. More recently there is a little collection in the Oxford Readings in Philosophy series called Free Will, I forget the editor. Richard Taylor, in his Metaphysics, Prentice Hall, as an important view. \\
This is all free will and determinism stuff. For What Is Determinism, and if you are into heavy going, John Earman, a brilliant philosopher of physics, has a book called Determinsim, discusses whether classical mechnaics is deterministic. Or are you interested in __historical_ determinism? --jks