And fourth, since the effective tax rate for Apple in the EU appears to be very much lower than in the US, I'd very much like to know why Apple charges the same in £'s as it does in $'s for products, in spite of an exchange rate of ~$1.30 to the £. When asked this before, the answer was always 'taxes'.....
As I understand it, here's the simple answer: VAT (Value-Added Tax).
Specifically, the published or advertised price in £ includes the VAT (if this is wrong, please correct me).
Conversely, in the US, none of the advertised prices includes any sales tax. Partly this is because sales tax is a State tax, not a Federal tax, so the amount differs by state, and some states have no sales tax. The other part is custom (tradition), in which retail prices always exclude taxes. Thus, we see car ads in the US that say in fine print that sales tax, license fees, dealer prep fees, and other charges are not included in the stated price.
So given the difference in how prices are advertised, and supposing a nominal state sales tax of 7%, and using whatever VAT your country imposes, calculate the actual difference in price given ~1.30 to the £. It's going to be a break-even around 20+ percent, but that's off the top of my head, without doing an actual calculation.
Note that the income tax paid by Apple in the EU (which is what the "Isle of Jersey" story is about) has effectively nothing to do with the VAT paid by EU consumers. The VAT is collected by the retailer, and paid to the government at some govt-designated interval (weekly, monthly, quarterly). Sales tax collection in the US works the same: retailers collect it, and make payments to the state each month or quarter. Those same retail businesses also pay Federal income tax, and State income tax in states that have it (again, varies by state). The amount collected as sales tax goes straight to the state; retailers are not taxed on that, nor do they count it as revenue.