Garden party formal or semi-formal for the ceremony! Fun, light springy colors and florals encouraged. Ceremony will be outdoors (weather permitting).
I'd anticipate highs in the mid 70's up to 80. It shouldn't be rainy, but when it rains here it pours and then clears up relatively quickly.
Nope. Wouldn't recommend it. The French Quarter is very walkable. The street car lines, public transit, and Lyft/Uber are the best ways to get around otherwise. There is all day parking available at various hotels but it can be pricey.
What a great question I'm so glad you asked. Bourbon Street is really Bachelor/Bachelorette party central. It oozes debauchery. If that's your vibe and you don't mind crowds, then you'll enjoy it! If it's not your vibe I'd recommend checking it out in the daytime to see the sights before the nightlife kicks in. Frenchmen Street is Faith's recommendation for live music and nightlife if you're over 30 :). There are MANY other gorgeous, historic, lively streets in New Orleans to visit besides Bourbon Street.