TAX RATES AND ALLOWANCES – “Not contracted out rates” means??

1 – What does “Not contracted out rates” infer under “National insurance contributions” in the TAX RATES AND ALLOWANCES section of exam question papers?
2 – What do the “Year”s as in “£1 – £5,715 per year” embody? 12 month periods OR Tax years?

I’d be thankful for any contribution!