#1, read the news. It's been prosecuted before.
#2, it's called professional ethics. Independent contractors have to have 'em, because their livelihood depends on their reputation. Corporate drones, less so--their 'reputations' hinge off the company's marketing.
#3, I accept cashier's checks and cash, myself. Only accept a personal check if you know the person and you can kneecap 'em if it bounces. Credit cards aren't really in the books for most independent contractors on the consumer-maintainence side.
(O'course, I try to -avoid- that side, myself; most of my contracting's done in other areas--but hey, if someone wants to pay me $60 to set up a printer and I have nothing else to do, I'm not about to turn it down, and at least when I do it I know it's done right).