The closely wound bits are the parts that compress for 80% of your valve lift. It's a dual rate spring. When the lower compresses fully, the top starts compressing, but it's much harsher, to ensure your valve changes direction quickly (ie: fighting valve float), then goes back to the softer as it unwinds, so that you're not smacking your valve seat too harshly.
And yes, the tighter coils should go at the bottom towards the head. Not for valve float, but less weight as noted above.