hanging around fields and on fences, 'chatter,' chirps, some sounds.

In the air, they're usually hunting, so some degree of stealth is advisable. Yes, they are mainly carrion-eaters, but if they can't find dead stuff, they'll go after live stuff--small critters, like mice, baby rabbits, etc. IIRC, black vultures will go after live animals more than turkey vultures will.

They can silently soar for hours at a time, but do also flap their wings. The main other sound Turkey Vultures produce is grunty hissing.