@ Raven- Another alternate replacement for lux I would suggest is the Athene's Unholy Grail item. It gives out a lot of ap (90), has CD reduction for dat laser, and is a good item to help with mana problems. It also has 40 MR to boot. I found that i was too mana hungry with Lux even when running Rod of Ages. But whatever suits your needs.
Another item replacement i would suggest is the void staff if the enemy team is stalking MR items I assume you were going to build a lich bane which is a good item i suppose. I never tried using the bane because its used mostly, i found, on mixed attackers who relies on a good burst, like Nidalee.
@Pride- My priorities for skill usage is R>Q>E>W. The shield is useful, but i found the level one shield can block out the effects of ignite and, if laning with someone like karthus, itll help his early games requiems. Her snare is incredibly useful when escaping too and can be used to go for the combo of Q>auto attack> E >attack> laser. But thats just my opinion