Is it obligatory for the husband to lead his wife in the two rak'ahs of marriage, or should each of them pray individually? And should the prayer be silent or audible? And is it recommended to recite specific surahs therein?

It is a Sunnah for the man and his wife to pray two rak'ahs together when he first goes in unto her, provided she is ritually pure. The recitation should be audible at night and inaudible during the day. In these two rak'ahs, they may recite whatever they wish from the Quran, such as Al-Fatiha and Al-Kafirun in the first rak'ah, and Al-Fatiha and Al-Ikhlas in the second.