(A) 'Perpetrate' is 'to commit a crime'; 'perpetuate' is 'to continue'. (B) 'Might' is 'great strength'; 'mite' is 'a very small amount'. It refers to contribution of even a small effort to the national cause. (B) 'Billow' is 'to surge or swell'; 'bellow' is the howl of an animal. (B) 'Burrow' is underground dwelling as of a rabbit; 'borough' is a (human) township. 'Pocket borough' is idiomatic.