Sure, Ireland did wrong by insinuating to Apple that they could have special treatment when in fact EU law prohibits it, but Apple failed to pay the prevailing tax rates which can be demanded long after the fact. Ireland has sovereign immunity from tort in this case. They could legislate to waive their immunity for tax assurances which would create an interesting constitutional issue in the EU.
EU law supercedes national law. Ireland can legislate as much as they want, but if they ignore ECJ judgements stating that their laws are incompatible with EU legislation, they will be fined.
Yes, potentially, but my understanding by following this case and others is that the EU has no legislation on taxes other than non-discrimination. So there is no EU law to supercede Irish law.
