By no means is this a complete list, but you might discuss:
* Getting ready:
Does everyone know where to get ready? Do they know what time to be there? Is there anything special they need to know (park in the back, bring your own mirrors, that sort of thing)?
* Payments / Gratuities.
I’m assuming your wedding planner is going to take are of getting final payments from you to the respective vendors. Who should the wedding planner speak with if there are any problems?
* Restrictions imposed by the venue.
Are bubbles, rice, alcohol, floral petals allowed?
* In Case Of Rain.
If it rains, how does that impact your wedding. What is the back-up plan in the event of inclement weather?
* Coordinate with vendors.
Your wedding planner should have a master list of names and contact numbers for each vendor from the bakery to the band to the photographer. The wedding planner should have a schedule for contacting each vendor in the weeks leading up to the wedding to make sure everything is going according to plan.
* What is the game plan?
What time do you want the photographer to arrive? How early can the band come to set up (give them at least 3 hours)? What time should the cake arrive? Does the caterer know what time to bring the food? Can they bring it early? Have a plan for each vendor and make sure the vendor and your planner are on the same page.
* Gifts and Cards.
Who is responsible for transporting gifts and cards from the ceremony to the reception and from the reception to the couples home? Do they have a key?
I hope that helps!