On the rice. Thin varieties like long grain Indian rice will need less water than the fat sticky rice varieties like Japanese rice.
It also depends whether you rinse the rice first. Some argue rinsing the rice washes away some of the starch and flavor. Others wash away. I rinse the rice a couple of times. i.e. rice in the cooker bowl, cover with water, slosh and drain. repeat.
I do Japanese rice at two 1/2 cups water to one cup rice. Of course this considers the fact that the rice is already wet from the rinsing. May need a half cup extra if you don't rinse.
You'll need to experiment a little with your cooker. If it is a little wet don't worry. Just make the rice early and let it cook out the water. Rice will stay in the cooker for a couple of hours before serving.