Simply put a plane there and texture it (but remember it must be double sided).
Modeling circular shapes for this only adds unneeded detail.
So yes, do it all using a single mesh. you can even rotate the rings using animations, as long as the plane is on a separate mesh group.
Mapping a texture onto a simple plane doesn't work in this case, because Orbiter will not render transparencies for planetary bodies.
Either way, I have a working model now, with the rings modeled with Chariklo itself. I have to say, it doesn't look half bad, it actually came out a lot better then I thought it would. Right now I'm just working on a custom surface texture for Chariklo (as opposed to reusing a texture from a previous add-on I've made), and I still need to tweek the physical properties themselves.
As for rotation, I luckily get to cheat a bit with this. There isn't any data on the actual rotation rate of Chariklo (they've tried to measure it before, but have to date been unsuccessful), but based on the shape of Chariklo (ellipsoidal), I think it is likely that it has a fairly high rotation rate, so I'm just going to set the rotation rate of Chariklo fast enough that it would match the orbital period of the main ring.
One thing I'm debating on whether or not I should do, is putting in a fictional shepherd moon. It is highly likely, that there is at least one shephard moon orbiting Chariklo, but none has been discovered yet, and it is likely to be small enough that it won't be discovered any time soon. The paper on the discovery of the rings even contains equations for calculating possible shepherd moon properties. It is of course possible that there's no shepherd moon, and that the rings are just very young, but the face there's a distinct gap in them, and the rings are well defined as opposed to diffused, leads me to think that there almost certainly is a shepherd moon in the system.