Is the current betrothal—which includes offer and acceptance, witnesses, and gifts, without mention of the dowry—considered an incomplete contract that must be completed, or a void contract that is no different from what is prevalent and necessitates a marriage contract before marriage?

The engagement is neither a valid nor an invalid contract; rather, it is merely a promise of marriage. The pillars of marriage are the two spouses, the offer (the guardian's statement to the groom: "I marry you to so-and-so" or "I give her to you in marriage"), and the acceptance (the groom's statement: "I accept this marriage"). Saying "I proposed to so-and-so" is not sufficient to complete the contract; rather, the wording of marriage or what stands in its place is necessary. The contract is valid even if the dowry is not specified.