What is the ruling on celebrating an engagement and what it entails, such as announcing it to people and exchanging gifts like the "bayan" (jewelry set) and the ring, all of which occurs before the marriage contract?

The ruling on wearing an engagement ring has been previously explained, as has the impermissibility of a suitor touching his fiancée. As for the young man and his family going to the prospective bride's home with gifts to announce the engagement, there is no objection to this as long as there is no Shariah prohibition involved, such as mingling with non-mahram (definition) women.