I can really understand your feelings of being used/abused by your administration. However all countries are short of nurses and all seem to recruit from overseas, nurses from Australia go to Britain Canada and the US and nurses from Britian come to Australia and so on ad infinitum. Its not the best way of obtaining staff since the travellers don't stay forever and as you have found out they do not encourage administration to provide policies that support their long term employees.
However I can speak from the perspective of the Australian nurse that came with an agency to the US. We were all experienced in our particular fields (ER for me) had passed Boards in California and were ready to work. There was no $10,000 bonus and we worked in a county hospital that was desperate for nurses. Coming from another country is difficult since you want to experience a different culture and get different nursing experience, but you have little control over where you end up working and don't know if you are walking into a facility that is poorly treating its staff or if you are being used for some other political reason within the hospital.
However there are significant benefits on both sides when people with different backgrounds work together. You discover many similarities in practice and a variety of differences. Working together both groups can learn new and different ways of doing things as it is easy to become parochial in your thinking- ie we do it this way so it must be the best way. Both the American nurses and US nurses found different ways of doing things sometimes worked just as well and many patienst found ou teh Australia was not a country inEurope with big mountains. I learn't so much in my year in the South, actually more about gun shot wounds than I ever wanted to, I found out what grits were and I still won't eat them' I know the rules of American Football and I found out that nursing is similar the world over and I made friends in the US which I still have 10 years later.
While I understand your distress over the treatment of the permanent staff by your administration, please realise taht teh nurses coming from Ireland probably have no idea what is going on and many may have a lot to offer.