'Haud facile emergunt, quorum virtutibus obstat
Res angusta domi.'
vetere, 'long-standing.'
vadimoniis, etc, alludes to the three stages of legal proceedings against a debtor. Vadimonium, security given for appearance in court; iudicium, the trial and legal decision; proscriptio bonorum, the confiscation of the property for the benefit of the creditors.
infitiator is one who denies his legal obligations; 'lentos' is added to point the antithesis to 'acres'; 'not so much keen soldiers as shirking defaulters.'
non modo, sc. 'non sentiat.'
carcer. The 'Tullianum' under the Capitol was the only public prison in Rome.
postremum, 'the last,' i.e. 'the lowest,' both in point of number and morality.
proprium, 'Catilina's particular favourites; his special choice,—let me say rather his most cherished and bosom friends.'
immo vero, see [on 1. 2].