Yep, you're correct, they were depth mapped. I ticked them off and they went away. Thanks Gen!
What kind of shadows is the light generating? Those look like depth mapped shadow artifacts.
Just a simple 3-point system, nothing special.
Yeah I'd go with raytraced shadows since they're more physically accurate than depth mapped, unless that's some kind of filler light that doesn't need to cast shadows at all (I don't know what kind of lighting setup you're going for).