  We calculate various tree-level (disk) scattering amplitudes involving gauge,
matter and moduli fields in type IIB toroidal orbifold/orientifold backgrounds
with D9,D5 respectively D7,D3-branes or via T-duality D6-branes in type IIA
compactifications. In type IIB the D-branes may have non-vanishing fluxes on
their world-volume. From these results we extract the moduli and flux
dependence of the tree-level gauge couplings, the metrics for the moduli and
matter fields. The non-vanishing fluxes correspond in the T-dual type IIA
description to intersecting D6-branes. This allows us to determine the moduli
dependence of the tree-level matter field metrics in the effective action of
intersecting D6-brane models. In addition we derive the physical Yukawa
couplings with their correct normalization.
