i squat in chucks which are flat. flat soled shoes allow you to get your hips into the movement. i find that healed shoes allow you to get more quads into the lift. it really depends on your type of squatting style and if you are a "hip" squatter or a "quad" squatter.
you definitely should be squatting in flat shoes.. the less the better for deads. i deadlift in my socks and use wrestling shoes when i compete.
i don't know about the close stance helping my deadlift. i squat with a just outside my shoulders stance.