That's a lot of questions. First, sometime between the end of September and the beginning of October, Sharkathon will be going on. You need to find when this is happening and not go on that week/weekend. There will be about a thousand people on PINS that weekend. That time of year on PINS can be very challenging due to weather, tides, red tide, etc. I have been down there every year for the past 3 years during that timeframe and coastal flooding has been an issue every year. We have had no choice but to pull our trucks into the dunes. Keep in mind that this is illegal unless there is an emergency such as coastal flooding. Park Rangers are constantly driving up and down the beach. You can also expect at least 3ft waves that time of year. Kayaking through them is sometimes doable but it is a challenge. I have witnessed severe injuries from doing this.
There is a sign at about the 4 mile marker that states only 4wd vehicles past this point. I have seen cars go past it and it's not a big deal. Keep in mind that the beach is constantly changing and what might be drivable one day may not be the next day. In my opinion, I would not go past the 15mile marker without a 4X4. Past the 15, it can get bad. Again, during that time of year it is normal for the water to go to the dunes so be careful and make a judgement call. I'm told that tow trucks will not pass the 4X4 sign at the 4 mile marker.
I would not leave your vehicles unattended. As far a camping gear, be very prepared. Outside the normal stuff (depending how far down the beach you go), bring fix-a-flat, an air compressor to pump up your tires, a few cans of gas (it's a long trip to the closest gas station), etc. I have a fishing/camping item list that I use as a reminder for things to bring. PM me if you'd like me to email it to you.
Just Bitten Shark Fishing Team