@KevinC9659 in answer to your question about calls to Irish mobiles while roaming in NI it looks like they are *not* covered by you membership/add-on call minutes allowances unless they meant to include UK/NI here when they say EU?
https://48.ie/legal/price-plan-details"Unlimited minutes for calls made to landlines including non-geographic numbers (1800, 1850, 1890, 0818 and 076) and mobiles within the Republic of Ireland and calls made while roaming in EU to other EU numbers and back to Republic of Ireland."