Hi Allen,
The meat, potatoes as well as the gravy concerning the 3rd Virginia Infantry is contained in the book “3rd Virginia Infantry” by the late Lee A. Wallace. I suggest that you get the 2nd edition of the book. Mr. Wallace, a diligent researcher, added a good deal of information to his sophomore edition. Seek it out.
http://worldcat.org/oclc/13992425&referer=brief_results
The 4th Virginia Heavy Artillery evolved into the 34th Virginia Infantry. See:
http://worldcat.org/oclc/43435973&referer=brief_results
These books, part of H.E. Howard’s Virginia Regimental Histories Series, are still available from various sources. Beware of sellers asking outrageous prices.
http://www.abebooks.com/servlet/SearchResults?sts=t&tn=3rd+Virginia+Infantry&x=23&y=7
http://www.abebooks.com/servlet/SearchResults?sts=t&tn=34th+Virginia+Infantry&x=46&y=6