Re: Sunglasses... I would put them on my hat until I needed them when I started running. Later, I got transition lenses that start out light enough I could get around in the dark.
Re: Hydrating... Just start early. (The day before is basically too late.) I really start paying attention a week out, and try to keep the pee clear(ish). If you're worried about sweating out too much salt in the Florida sun, electrolytes won't hurt.
Re: Vitamin C... I can somewhat vouch for this. I used to play tennis in the Alabama midday summer sun quite a lot, and I would have an Emergen-C packet after. Now, this could have been because I wasn't fueling properly while playing. (Knowing what I know now, I should have been doing quite a lot more! That would have been a game-changer.) But the vitamin C kept me from getting horrendous headaches after a match. And yes, protein is a good idea, too. Your body is screaming out for sugar and protein after you get done, and it's best to get that in within a half hour of finishing.