Ireland has adopted the Euro, fixed at the rate: Irish Pounds 1= 1.27 Euros.
Ireland's income tax rates are lower than most of its EU counterparts, thanks to reductions in recent years.  The budget of 2001 reduced taxes but also caused the EU to formally reprimand Ireland for implementing a budget which is seen as being out of line with EU policy.  The HR Department of your new company in Ireland should be able to tell you all you need to know about tax rates; or you can have a look at the Revenue Commissioner's site.  For a quick idea of how much you'll earn and how much tax you'll pay, check the currency calculator and the tax calculator.  

Ireland also has one of the lowest rates of corporation tax in Europe which is a major attraction for foreign investment.
Learn about PRSI (Pay Related Social Insurance) at the Department of Social Welfare.