If your wedding reception is being arranged thru DFTW, then your EM will arrange the cake for you.
The staff of the GF Cafe very rarely do receptions, and are unfamiliar with the procedure of ordering cakes, presentation, and service of said cake (i.e. cutting properly, removal of fondant if need be, etc.) If you have a large group, then you really should contact them and see if they can accomodate you. As far as the cake itself, the GF bakery can only supply a stacked 2 tier cake for this restaurant, as they usually do not have the space for a typical wedding cake set up and display. Your cake would be brought out after your meal and cut then.