My apologies Madam. I suggest you start with yourself and work backwards toward your James Kirk. Make sure you have soldid proof of who each individual is and their names, dates of birth and death sand all locations possible. Once you have done this you info will lead you to the correct CSA soldier. Lets not worry about the NC bunch at this time, just find your g-grandfather and his unit.
The war records generally show, when a man enlisted, where and by whom.It tell the dates of muster, present or absent, sick to hospital or death and cause. These are oonly general information. Sometimes a pension record gives more detailed information.
Many men changed units, so yes, it is possible a man will show up in different units and be listed by more than name. I think James Kirk of the 29th stayed in that unit the entire length of the war making the rank of SGT.
Here are some links that should help you find your ancestor and his family. You may have to copy and paste the link to get it open.
http://pilot.familysearch.org/recordsearch/start.html#surname=Bull;searchType=standard;p=1;placeId=54;givenName=James%20H.;eventPlace=Mississippi%2C%20United%20States
http://www.familysearch.org/eng/default.asp
http://genforum.genealogy.com/kirk/
I'll see what I can find later tonight or tomorrow.
GP