I hate to disappoint you but it has no Irish Gaelic spelling. In fact it's not even Irish: it is a Welsh name, a pet form of Margaret. It's original spelling is Megan [meg-an]. I suppose it's similar to Caitlin/Katelyn: an American phenomenon. The "name books" used in the USA are full of misinformation. The closest Irish name would be Peig or Peigín.
With the accent marks: Írusán [eerusaun] in Irish.
In Irish Gaelic: an oiche. (Accute accent on i) In Scottish Gaelic: an oidhche
There is a Gaelic website translator that will teach you to say it in Gaelic or you can just say it in English with an Irish accent and for that I recommend Boondock Saints
In Scottish Gaelic: fìrinn (mind that the accent is grave, not acute like in the Irish)
gach rud everything In Irish
The Irish Gaelic translation for Daddy's Girl is Peata Dhaidi
Be aware that 'Gaelic' is actually two separate languages: Scottish Gaelic (called 'Gaelic' in Scotland) and Irish Gaelic (called 'Irish' in Ireland).In Irish: gadhar rua or madra rua (the latter can also mean 'fox')In (Scottish) Gaelic: cu ruadh.
Is mo chuid den tsaol thú
Íocfaidh mé as gach rud.
Irish: f-yunn (N & W) f-yoon (S) Scottish:
I will pay for everything.
Brotherhood before everything