This is tricky business. If all you want are bodies on the water, go with the cheapest dekes you can find. If you are like everyone else I know, you won't be happy with them after the 1st season. Decoys are like anything else, you get what you pay for. When the Avery dekes came out I had to have some because they look so realistic.
After about 2 hunts that georgeous paint started chipping off of their heads, I should've known for that price they were too good to be true.
Last season my buddy bought the new flambeau's, same thing.
I would recommend G&H's, if you start at the top you won't have anywhere to go and I guarentee you that's what most of us don't do.
As for cord get tangle free any brand it doesn't matter.
For weights your best bet is the mushroom type or the straps.
I've used everything and that's the best way to go, when they came out with the stretchy ones I was smitten, after a season the rubber part wears out and then they suck, that's why in catalogs where they sell them they always offer replacements.
G&H may not be the best out there, I know some would argue, but Blackwater's are like 175.00 for 6.
As far as numbers go, it really depends on the size of the water you are hunting, and believe it or not, hunting pressure.
I would stay away from the package deals because that's the best deal for the MFG. not the buyer.