1. the person who opened the drapes did not necessarily have to be the same person who killed the hitters, and likely was not. The more I dwell on this question the more likely I believe it was Fredo who would have had access to the inner sanctum of the house, and he did it on Johnny Ola's orders.
I doubt Fredo, as the official underboss of the family, would be taking orders from Johnny Ola.
3. I think they were dragged to the drainage pipe, so it didn't matter if there was a grate. They were already dead. Maybe if there wasnt thats how the other conspirator got out.
It would be a pretty balsy and kind of retarted move to drag the bodies all the way to the drain pipes after the failed hit. Within minutes after the hit the place was crawled with bodyguards and German shepherds.
