You have to pay yourself enough paye to pay ni, can't not pay ni, you just pay less than if you took all money as paye.
Less tax. You don't pay NI. Need to be earning over 40 000 roughly to make it worth while because accountancy fees increase dramatically and paperwork. If earning enough profit it will save you a fortune.
Might be wrong but i thought the 10% tax relief on dividends got stopped a long time back.