Áistín is ainm dom / Is mise Áistín / Áistín atá orm
Aibhistín
Austin. As a name it doesn't change
The French translation for Austin is "Austin". The name remains the same in both English and French.
Johnson is not an Irish name. This is not to say there are not Johnsons with Irish ancestry. So no Irish county is associated with the name Johnson.
Roibín
The form used in Irish is Heather as in English.
match-you
As a male name, Dónall.
Yeah I would say if was
YES! Some say it's the Irish version of Charles, but that is not true.
Devin in Irish is 'Dubhain's Heir'. It is a very popular boy name.
If a given name it would stay the same; no Irish equivalent.