  In this paper, we continue our study of form factors and correlation
functions of gauge-invariant local composite operators in the twistor-space
formulation of N=4 super Yang-Mills theory. Using the vertices for these
operators obtained in our recent papers arXiv:1603.04471 and arXiv:1604.00012,
we show how to calculate the twistor-space diagrams for general N^kMHV form
factors via the inverse soft limit, in analogy to the amplitude case. For
general operators without $\dot\alpha$ indices, we then reexpress the NMHV form
factors from the position-twistor calculation in terms of momentum twistors,
deriving and expanding on a relation between the two twistor formalisms
previously observed in the case of amplitudes. Furthermore, we discuss the
calculation of generalized form factors and correlation functions as well as
the extension to loop level, in particular providing an argument promised in
arXiv:1410.6310.
