“The first mishna in Kiddushin may be a nice place to start studying the kinyanim that apply to marriage”
the danger of superficially learning a sugya, or making assumptions about what other people write. there is erusin, there is nissuin. weddings “today” include the components of both erusin and nissuin. learn the sugya and the many opinions in the rishonim as to what contitutes nissuin (and even erusin) nowadays.