Can anyone help me out with information about safety, rules, etiquette, etc...?
If you've taken your hunters safety course, this should be quite evident for you.
Safety is always #1, no matter what.
Etiquette - don't crowd others, give them at least 100 yrds buffer, more if possible. If they are working birds, and they
swing over you, to go to their decoys, don't shoot at the birds, it's called respect.
Don't skyscrape, in other words, learn to judge distance, don't shoot at birds that are beyond 40 yards or so, the closer the better. If it means you have to pass up a shot or two, then so be it. We all get excited, but it's the once that know restraint, that end up doing better.
If you don't know how to call well, then don't, let your decoys do the work for you.
As for the marsh, get out there and do some exploring around. No one is going to tell you where to go exactly, you need to get out there and poke/look around. Take a day or two, and like I said, go exploring, get a feel of the lay of the land, it's a lot different at 4:00AM. Find some likely spots, and go hunt them when you get a chance.