If one state didn't offer a tax break, then another would and win the business. There are 50 states, and most of them compete for businesses with tax incentives fairly competitively.
It is possible that the bribe-for-tax-breaks exchange actually provides benefit for the community, but that's not necessary for the transaction to take place.
No, it doesn't.
Every country in EU sets it's own corporate, sales & income tax rates. as well as _EVERY_ other rate.
Every country in the EU can & does offer incentives & future tax payment agreements to companies who meet certain conditions. These are not inter-EU agreements nor do they need prior approval by any EU establishment.
Apple is always "going to pay", but they never did (and wouldn't make sense in any way), and Ireland also haven't paid and it doesn't look like it is.