No, use light extract. It's more fermentable, so you'll get the most "bang for your buck".
Sorry if I'm preaching to the choir, but I thought I'd give my 10 second starter lecture: Don't use an airlock. Cover it loosely with foil or use a foam stopper instead. Shake it up as often as possible to get oxygen to the yeast. If time allows, put it in the fridge overnight before brewing, pour off most of the starter "beer", then pitch.