Red wires are bugged in the multiplayer just now (incidentally, does anyone know what last night's update did, if indeed there was one?). I've not used it at all in single player.
How does mercenary jobs work?
Someone hires you to burn other people property? (only outlaws?)
A couple of ways - Firstly, an agent of the state (currently just Wampbit and I) may hire you to take down an outlaw building. Secondly, any other player (via a sign in the marketplace) may advertise the need for a mercenary needed. They can hire anyone to do any of their dirty work for them, but if they want you to break the law in the city you better make sure it's worth the risk.