Why does it say "va'Yikach Es Leah"?
Ohr ha'Chayim: He forced her, or needed to persuade her. She did not want to trick Yakov!
Why does it say "va'Yavei Osah"?
Ohr ha'Chayim: He did not give her (like is normally done) to his messengers or to Yakov's, to minimize the time for Yakov to recognize her.
Regarding Rachel (verse 28), it says that he gave her to Yakov "l'Ishah". Why does it not say so here?
Ha'Emek Davar: Leah was not his wife until he knew that it was her, and consented.