The Sunset Pau Hana (Wednesday) and Welcome Dinner (Thursday) are both casual and the wedding ceremony and reception are formal.
The best airport to travel in and out of is the Kahului Airport (OGG)
There won't be dinner, just light appetizers (mostly sushi bites!).
Yes!
The Andaz Maui at Wailea, Four Seasons Wailea, Fairmont Kea Lani, and Marriott Wailea Beach Resort are all convenient hotel options. Airbnb and VRBO also have houses and condos available and are generally much more affordable than hotels in Wailea.
There are ubers and lyfts but they're not as dependable as they are on the mainland. Hotel Wailea does offer a shuttle for hotel guests for travel within Wailea.