Florists don't stick around for this function unless prior arrangements have been made. The only thing you need to remember here is that when the photographers' entire livelihood depends upon their reputation as a wedding photographer, they have a vested interest in doing the most complete and satisfying job for you possible. It really doesn't matter if a photographer has worked at the specific locations you are using before. Often the photographer will gladly arrange to meet with you on this pre-visit and do a walk through. Doing this gives the photographer a complete overview of the day and aids in the smooth progression of your entire photographic experience.
Many photographers now have websites.
You can find A LOT of information on the internet about photography as well as all other facets of your wedding.