Grasp of Undying is for survival, also it will deal magic damage. It stacks on your hp but dont worry about it too much, doesnt matter that much if you have 3k HP or 2K. it will still help you alot early and in late game. You will survive longer in lane, meaning more CS for you :)

Max E.. why? it deals more dmg if you max it, and the more skill points in this spell the more attack speed you get after using it.

E is also more easier to connect to your enemy, meaning in a game you come to gank when they have 30% hp, you land your weak lvl 1 e and 1 q and they flash away. if you max E your E will deal 4 times more dmg and so they will die after you get your 80% attack speed combined with your ad items.