  We investigate in detail the topological gauged Wess-Zumino-Witten models
describing topological Kazama-Suzuki models based on complex Grassmannians. We
show that there is a topological sector in which the ring of observables
(constructed from the Grassmann odd scalars of the theory) coincides with the
classical cohomology ring of the Grassmannian for all values of the level k. We
perform a detailed analysis of the non-trivial topological sectors arising from
the adjoint gauging, and investigate the general ring structure of bosonic
correlation functions, uncovering a whole hierarchy of level-rank relations
(including the standard level-rank duality) among models based on different
Grassmannians. Using the previously established localization of the topological
Kazama-Suzuki model to an Abelian topological field theory, we reduce the
correlators to finite-dimensional purely algebraic expressions. As an
application, these are evaluated explicitly for the CP{2} model at level k and
shown for all k to coincide with the cohomological intersection numbers of the
two-plane Grassmannian G(2,k+2), thus realizing the level-rank duality between
this model and the G(2,k+2) model at level one.
