Please arrive in dressy casual attire. A summery cocktail dress or slacks with a button up are both appropriate options. If you're stuck, here's a guide that might help: https://www.theknot.com/content/what-to-wear-dressy-casual
Yes!
Let's go to Tierney's Tavern after! It's nothing official–we requested their private room, but it was already booked for a band. We'll just be mingling with the regular customers. It's about a 10 minute walk from the reception.