By describing a technique that is well known but not actually used by apple you are confusing the situation
1. apple does not employ shifting funds through the Cayman Islands or Caribbean islands
2. Apple does not shift revenues paid in the usa to Ireland
3. Funds "stored" in Ireland can either be used offshore (e.g. Build an apple store), or they sit there waiting to be repatriated. They will be brought back to the us if rates are lowered or a tax holiday is created.
1. Apple does funnel money through Caribbean tax havens (via Braeburn Capital).
2. Not true, "Apple has set up a cost-sharing agreement with its Irish subsidiaries that gives them a disproportionate share of the profit from research and development that occurs in the United States."