Are Contracting Officer's data managers by default? or do they require special training?
DD 1423's are normally signed by the requirements office. Each organization may have their own approval authorities. For instance, I found this from NAVAIR on the 1423 instructions, http://www.navair.navy.mil/nawctsd/Resources/Library/Acqguide/cdrlprep.htm
Contracting Officer's are not data managers by default. See DoD 5010.12-M for detailed instructions of the DD Form 1423.