2) have you considered this birth? The name, age and father's occupation seem to match although the father's Christian name and location don't.https://www.irishgenealogy.ie/files/civil/birth_returns/births_1881/02840/2040903.pdf
Here is the newspaper announcementhttps://www.findmypast.co.uk/image-share/8bbac859-02ad-4021-a8ce-828b906853a4Isaac is deceased, and of Raymochy, Manorcunningham, county Donegal