Clothing/Shoes/Weather Gear: When it comes to the weather in the greater Tampa Bay area, summer is the norm. Make sure you bring clothes for warm weather as you are almost guaranteed several temperate days. Toward the end of October, however, there are a couple days that might actually fool you. On the night before I flew it, it dropped to 62! It was quickly back up to 75 the following day, but make sure you bring a windbreaker just in case for the evenings or a cold day.
It would be odd to find yourself in a setting that isn't casual here. Pack accordingly. Still, if you're at all concerned, take something that would be classified as "business-casual." In the better restaurants, this will work great with dress codes. I shouldn't have to mention this, but I've witnessed it, so.....DON'T show up in the nicer places in a tank top and/or thong! Enough said?
Toiletries and Medical Supplies: Take (& use) sunscreen. Don't buy it there. It's expensive.
Photo Equipment: You know what you need. Of course, just like sunscreen, film is expensive here, too.
This is a very casual area. Most restaurants allow shorts, and at those that don't, khakis and a collared shirt would be fine. Some nightclubs may not allow tank tops, sneakers.
Toiletries and Medical Supplies: SUNSCREEN, SUNSCREEN, SUNSCREEN! Waterproof is best - one of the 'sport' recipes is what I prefer. Sunglasses are also essential, and a hat isn't a bad idea if you're out in the sun all day (i.e. on a boat or beach). If you have plans to be outside in the evening, mosquito repellant may be useful. But if you forget any of these things, there are tons of grocery, drug, and discount stores around.
Camping/Beach/Outdoor Gear: If you are going to the beach, a pair of inexpensive 'surf moccasins' are a good idea. Some beach areas have rocks/shells that you need to get thorough before reaching the sand bottom in deeper water. (These 'ouch' zones shift from year to year due to storms and water currents.)
Miscellaneous: Pack a little bag to tote your lotions, towels, etc. to the beach. Also, zipper-close plastic bags are great for shells, wet swimsuits, leaky suntan oil, etc..
Since the main attraction is the beach, then you must not forget your swim suit. However, there are lots of shops along the beach that sell swim suits, shorts, and tank tops.
Toiletries and Medical Supplies: DON'T FORGET THE SUNSCREEN! The sun was intense there. Even if you have visited the tanning bed I would still suggest a minimum SPF of 15.