Sleep isn't even remotely broken.
I agree, note that it effects anyone, and unless you are metagaming heavily the caster does not know exactly how many HP the fighter has vs the goblins swarming around him. A good spell at low levels but it should be if it costs a slot.
The necro thing as well, I understand that there is no mechanical limitation on it but this is a RPG, why would a DM let a player hang out in a graveyard for a week unmolested while they perform unspeakable acts before every adventure? Suitable corpses don't grow on trees and marching an undead horde through town seems unwise.
It is odd that some summons are in the 4e action economy and others seem to be in the 3e mold.