Since at least some of your hunting will be in flooded timber, I'd have to recommend puddle duck decoys. Because everybody has mallard decoys, I'd go with something a little different....like half a dozen gadwall. Mallards will come to gadwalls, just as gadwall will decoy to mallards.
If you are in the right spot, six decoys will be enough. If you are not in the right spot, you could have 7 dozen and still not get shooting.
You will be able to decide what/how many to buy as you gain experience.
Brand? What is your budget??? If money is tight, get GHG Hot Buys. For a few dollars apiece more, either LifeSize, or for a little more yet, the ProGrades. If you have a bit more to spend, look at the new Avian-X. I use all of the above, and they work. I wouldn't recommend the Flambeau Storm Front mallards, but the StormFront pintails are as good as they get.
Hint: when rigging those new decoys, use line that is at least 1/8" in diameter, preferably braided nylon. Don't cheap out and use monofilament fishing line; you'll regret it. I also don't like Tanglefree line; it takes a set and seems to always be half out of the water.