Difference fields and descent in algebraic dynamics, II

This second part of the paper strengthens the descent theory described in the first part to rational maps, arbitrary base fields, and dynamics given by correspondences. We obtain in particular a decomposition of any difference field extension into a tower of finite, field-internal and one-based difference field extensions. This is needed in order to obtain the "dynamical Northcott" Theorem 1.11 of Part I in sharp form.