Yeah, darkness can be bought with no range, target self only and the effect moves with the charater.
Thats the effect I'd want with the Change Enviro as well. I don't see this effect as an advantage but a limitation so I'd not go with Usable As Attack.
As to the Electrokenisis, forget all the attack powers it's the manipulation and control of the electricity I'm interested in.
Pyro could shape fire at will, ok most of the times you saw him do it was with an attack (yeah special effects come to mind too) but whats the best way to model the manipulation bearing in mind that touching it would still still give an electro shock (damage shield).
Mike