On the salt water- just get out there and start doing it. For trout and red fish you can use your regular stuff in most instances- just wash it REAL GOOD to get off all the salt.
On the john boat- in fishing bigger is better IMHO. A kayak is okay but it shines mostly for situatons where that's all you can use. If you can use a john boat and motor- I think most times that's better- more interior room for all your stuff.
I tried snipe down at Webb last year but only saw four, shot at two and missed both. PM me if you find any good snipe areas here in central FL.