Some thoughts and experience:
After Ivan or was it another storm, I get them mixed up, the only way to get information was SoWal. The county was useless.
Another thing don't wait for the county to tell you to evacuate. We always leave early and it has served us well, we go to Birmingham, have heard too many horror stories about spin off tornadoes in Dothan.
We were in Rayne, Louisiana, just west of Lafayette, after Katrina, the land lines there were out for a day or two, after that it was spotty, cell phones worked better. Strange thing is that from Rayne I could call Baton Rouge after a couple of days but could not call Hammond. My SIL in Baton Rouge could call my sister in Hammond, so we had a phone call relay.
Seems like water is generally the big issue with even the larger storms. With Katrina the wind had dissipated when it came ashore so it hit at a lesser number, don't remember exactly. But the storm surge had built up from a cat 5.
Specific areas affected by flooding will also depend on where the eye goes over. If the eye hits to the east flooding will be worse on the bay. If the eye moves ashore to the west the opposite will likely occur. However the beach will be impacted no matter where the storm hits. Remember Opal cut so many beach houses in half, even the concrete ones that had been there since the 50's.
My prediction is if we get a 4-5 storm surge in South Walton the biggest problem will be all the debris from the seawalls that people think will protect them.
Something I just remembered. My Mom was living in Old Metairie during Katrina, she had evacuated early thank God. But the only way to find out if she had been flooded was the Times Picayune message board and google earth. It was amazing how fast google earth had maps up. I imagine that social media will be the best source of information after a storm, its so much more sophisticated now.