Is it permissible for a man to lead women in prayer if he has visited them to discuss a religious matter in a non-Muslim country? And must the prayer be made up if it was makruh (disliked)?

It is permissible for a man to visit foreign women if there is a need, provided that there is no fear of temptation; otherwise, it is not permissible. As for his leading them in prayer, it is considered disliked by a group of scholars unless there is a significant need or if the woman is accompanied by another woman, thereby negating seclusion (khalwa). The prayer of both the imam and the women is valid, even according to the view that deems their following him in prayer impermissible.