Currently there is a light controlled by a light switch. The light switch also has a gfi outlet adjacent to the switch. I want to add an outlet next to the sink. Can I run a line from the light? Or where do I get the power from?

If you run from the light, the gfi will work only when the light is on, if you run from the gfi you can run a regular receptacle off the load side of the gfi and will have power all the time.