Yes, ask about the Amtrack train and bus schedule in New London, CT for those who are attending by train.
Ask about the local hotels and if they have blocks of rooms at discount prices for your out of town guests.
Ask if there is a casino bus for those who wish to partake in the local Foxwood Casino or the Mohegan Sun Casino shows and what not. Depending how long you plan to stay in the Mystic area, the casinos are a great experience and you need not gamble because there is so much else to do there.
A qualified wedding planner will not even give you a chance to ask questions because they should be asking you pointed questions about your selections and what you want because THEY take care of the details.
But the usual things, like where is the ceremony in comparison to the reception and can you have the ceremony at the vendor location (the Flood Tide in Mystic has a lovely area to wed, inside and out and so does the Seaman's Inn at the Mystic Seaport) So, you will need to know about linens and centerpieces, a cake, music and photographers -- all the usual requests for a wedding. The wedding planner will have a list of local establishments which typically work with the local vendors as they have a trusted symbiotic relationships with other professional services.
I am very well acquainted with the Mystic, CT area and you have selected a great time of year to have a wedding in Connecticut as the area has many attractions and the water views are spectacular.