In the present paper it has been shown that the method reported in I, for the derivation of Schrödingers’s equation, can be generalized in such a way that essentially all aspects of non-relativistic QT are taken into account. The success of this derivation from statistical origins is interpreted as an argument in favor of the SI. The treatment of gauge fields and spin in the present statistical framework led to several remarkable new insights. We understand now why potentials (and not local fields) occur in the field equations of QT. The non-uniqueness of the potentials and the related concept of gauge invariance is not a mystery any more. Spin is derived as a kind of two-valuedness of a statistical ensemble. The local forces associated with the gauge potentials, the Lorentz force and the force experienced by a particle with magnetic moment, can also be derived. Apart from some open questions in the area of non-relativistic physics, a major problem for future research is a relativistic generalization of the present theory.