I am getting ready to plan the Rehearsal Dinner, but this is my first time doing this

so I don't really know what to do.... Do you find a restaurant that can accommodate all the people that will be there, and have a private room? Do you just order food/drinks from thier menu, or would the restaurant come up with special catering that you would need to plan for with them ahead of time? I have only been to one rehearsal dinner and they had a private room wtih a buffet of food. I feel like that's pretty much like how the wedding will be! So basically I have to do it twice? Anyone have any recommendaitons for places in Frederick? Thanks!