Frontier Worker in Ireland (UK Tax Resident) - Taxation

I have just transferred to a new role based in ROI (Dublin). Unfortunately due to circumstances out of my control I had to make the decision without being able to speak to company provided taxation experts/advisors. I will work in Ireland Monday - Thursday before returning home to UK Monday night where my Family and Family home will remain. I believe this means i'll likely be deemed a UK Tax Resident. I understand there is a UK Double Tax Treaty between UK and Ireland which will allow me to claim my Irish paid tax back towards my Tax Owed in UK as worked out in UK Self Assessment. A few questions hoping to get clarity on: 1 - Is there any way to claim back NI or Social Security contributions in Ireland towards same owed in UK? 2 - If I pay more tax through IE PAYE than I end up owing in UK, is that extra paid effectively lost? No chance to reclaim it somehow? 3 - I receive Stock Units as part of my compensation package. I've got UK granted stock units and will receive Irish grants as well. It seems I am liable to IE Tax on ALL my grants (UK and IE granted) as they vest each month but not eligible for Real Time Foreign Earnings tax credits as not a IE Tax resident. Is there any way around this? Extra info - I have set up meetings with a couple of tax experts to discuss further but not until 2nd week January. Unfortunately I've already been 'stung' by a large stock vest that has been taxed in both UK and Ireland Thanks

Hi
1. you would need to contact the NI office to discuss this  
2. if more tax is paid in Ireland, you would need to contact the Irish tax authorities to arrange a refund of excess tax  
3. you will need to contact us direct to discuss the type of stock units received to confirm if any relief is due