The medium modification of kaon and antikaon masses, compatible with low-energy kaon-nucleon scattering data, are studied in a chiral SU(3) model. The mutual interactions with baryons in hot hadronic matter and the effects from the baryonic Dirac sea on the masses are examined. The in-medium masses from the chiral SU(3) effective model are compared to those from chiral perturbation theory. Furthermore, the influence of these in-medium effects on kaon rapidity distributions and transverse energy spectra, as well as the flow pattern in heavy-ion collision experiments at are investigated within the hadron-string-dynamics transport approach. Detailed predictions on the transverse momentum and rapidity dependence of directed flow and the elliptic flow are provided for at within the various models, that can be used to determine the in-medium properties from the experimental side in the near future.