Concerning global affixes, this is currently not really supported by pandoc, as this is clearly not included in CSL. (Biblatex knows global pre- and suffixes, so this might come from there.)
Anyway, pandoc parses this org-mode-citation [(cite): PREFIX; @doeA; cf. @doe p. 4; SUFFIX] as:
,Para [Cite [Citation {citationId = "doeA", citationPrefix = [Str "PREFIX"], citationSuffix = [], citationMode = NormalCitation, citationNoteNum = 0, citationHash = 0},Citation {citationId = "doe", citationPrefix = [Str "cf."], citationSuffix = [Space,Str "p.",Space,Str "4",Str "SUFFIX"], citationMode = NormalCitation, citationNoteNum = 0, citationHash = 0}] []]]
The global prefix is merged with the first citation’s (non-existent) prefix, the global suffix is merged with the second citation’s suffix.
(Perhaps explicit support for global affixes would be something to be discussed for CSL 1.2, or later…)