Must I repeat past prayers due to not thoroughly conveying water to the face during wudu and wiping over the hijab, and how should I deal with this issue in the future, and what is the ruling on water reaching the eyelashes during wudu?

The obligation in washing the face is to let water flow over it such that it covers the entire face, and merely wiping with the hand is not sufficient. The eyelids are included in the boundary of the face and must be washed. For thick hair that does not show the skin, it is sufficient to wash its outer surface; otherwise, it must be washed along with the skin. There is no concession for wiping the face for a woman wearing a khimar (head covering). If you are certain that you are not washing the areas next to the ears or the eyelids, or if you are only wiping without letting water flow over the face, then your wudu' (ablution) is incorrect. You must repeat the prayers you performed with that wudu'. If you are unable to ascertain their number, you should act based on estimation and perform enough make-up prayers to achieve certainty or a strong presumption of having cleared your obligation.