Really depends on climate and location of the coop - in the wrong location, a see through roof can turn a coop into an oven. Also in most cases chickens will spend the majority of the day out in the run or free ranging, so they'll get plenty of ambient light exposure that way.
Roost bars only really need to be higher than nest boxes, so a couple feet up is fine.
Bars should be at least 14-16" away from each other, and at least 12" away from the wall.