Made hams and bacons with wet cure process for many years at my dad's store.
Essentially, the only ingredients you need to use are:
water, brown sugar, white sugar, salt and cure.
For every 1 gallon of brine add:
1 cup brown sugar
1 cup white sugar
1 cup plain salt
1 tablespoon cure no. 1
with hams and pork shoulder picnics you have to pump the brine into the meat so it cures from the inside-out as well as the outside-in, otherwise by the time it gets into the center of the meat it could be spoiled (known as "sour-bone"). That's easily accomplished with a simple brining pump that's not terribly expensive ($29.99). You can order both the brine pump and the cure from Butcher Packer:
http://www.butcher-packer.com/index.php?main_page=product_info&cPath=2_45_231&products_id=25 meat brine pump
http://www.butcher-packer.com/index.php?main_page=product_info&cPath=237_12&products_id=56 curing salt
There is also a 'cure no. 2' but that is for fermenting meat under controlled temperatures, like dried sausages, etc.; totally different useage.
At the bottom of this post is a link to my post about making my own ham, recreating the process that my dad did making thousands of hams a year at his store. It gives instructions on how to trim and pump the ham, letting it cure, smoking it, and preparing it for Easter dinner last year. Almost time to do another for this year!
No other preservatives are used, only what is in the cure which is what is necessary for the curing process to occur.
Hope this helps and have fun doing it!
BTW, Craig and I grew up together!