Athermal solutions of semiflexible macromolecules with excluded volume interactions and with varying concentration (dilute, semidilute, and concentrated solutions) in a film of thickness D between two hard walls have been studied by means of grand canonical Monte Carlo simulation using the bond fluctuation lattice model. In earlier work, we have reported on the phase diagram of this model system, which exhibits a continuous quasi-two-dimensional order-disorder transition at rather small concentration and (for thick enough films) a "capillary nematization"-type first-order phase transition. In the "semi-infinite" case (i.e., macroscopically thick films) the onset of nematic order is triggered by the walls (surface-induced ordering). While the focus of this previous work was on the order parameters of these phase transitions and associated surface effects, in the present paper we focus on the interplay between the conformational statistics of the semiflexible chains and these orientational ordering phenomena. In particular, we study how characteristic lengths of the chains (persistence length, end-to-end distance) depend on the local and global orientational order in the system. We show that there is a strong coupling between single-chain properties and long-range orientational order. The relation between mean-square end-to-end distance of short semiflexible chains and their persistence length predicted by the Kratky-Porod model is found to be applicable (within 10% errors) in the dilute limit, while it fails as soon as nematic short- or long-range order is present.