Sumarian. There is no proof to back up any claim reguarding this question.
http://www.linguistlist.org/ask-ling/oldest.html
Earlier, Latin. But then they started to speak Greek.
The primary language of the Irish Republic and N.I. is English. The native language of Ireland is called Irish (Gaeilge) by the Irish and 'Gaelic' by non-Irish. It is a community language in parts of...
social norm
Yes, though there are dialect differences.