I personally don't like walking through rough turtle grass. It catches the hair on my legs and scratches me all up. Plus, weaing long pants keeps the shells and rocks out of your shoes if you tuck them in! So, I wear pants when I go out shrimping. Jeans are too heavy so I choose to wear something a bit lighter. I recently purchased the Columbia Titanium outer wear pants. The are very light, dry extremely quickly and wick water away.
For a battery pouch, I use a JanSport fanny pack. They no longer call them that on the JanSport website but they are basically the same thing. They can hold two batteries comfortably around the waist, some spare light bulbs, a pack of cigarettes if that is your thing, and a beer (or two) if you are lucky enough to get a big one. They usually have a wide quick release tab and are adjustable for different waist sizes. Other options are to use a full sized backpack. I don't like this option because it hurts my back after a few hours.
Shirts with lots of pockets are also a good thing to have. You can store extra's in there like knives etc. Columbia's Professional Fishing Gear has just the thing. I got mine on sale at Sport's Authority during the middle of the week. They usually mark them down during that time.
Speaking of knives, it always helps to have some type of tool with you on the water. I personally carry a Leatherman with me just in case I need to fix something or cut something out on the water. I have seen others carrying full size dive and fillet knives, gigs for flounder and even fishing poles. Some people have gone so far as to create a floating toolbox on a foam slab or a flats caddy complete with pole holders, bait bucket, cooler, radio, dry box, tackle box and assorted gadgets. I'd say that you have a bit of a problem at that point.