The best advice I can give you, and the greatest help for you is to hunt with someone who has hunted turkeys for many years, if you can.
This is only my 2nd year turkey hunting(and why I didn't go 20 years ago I'll never know)so I won't be much help, but I found that a slate call, or box call, is the easiest to learn how to use. The best sounding slate call I've ever heard is one I bought this year, an HS Strut Ring Zone(Wal-Mart). It sounds absolutely great. There are three styles of the Ring Zone, a slate, a glass, and a ceramic. I can speak for the slate, and they are supposed to be "scientifically proven" to resonate at the same sound range as a live wild turkey. I have a Quaker boy box call which sounds really good. Mouth calls were very hard for me to learn to use, and I found that the HS Struts were the easiest. I'm sure many will have differing opinions on their favorites, but as a beginner these were what I came to like after much trial and error. Another tip is wait until after season is over when Wal-mart marks all the turkey stuff down half-price and then stock up and figure out what you like.
You can get an easy to carry hen decoy at Wally world also for about $10.
The National Wild Turkey Federation has a website and you can listen to just about all the turkey sounds to practice calling by.
http://www.nwtf.org/for_hunters/Also, most definitely, get you a good recoil pad for your H&R. You'll see what I mean after the first 3" magnum turkey load. The full choke should be fine out to 30 or 35 yards which is plenty good enough.