It might take a while. I cant imagaine something changing sexual organs very fast. It would be a shock if it happened over night. "marvin, why are all these guys hitting on me?"
I could imagaine an octopus could easily lift a lid off a tank. You would have to put some massive weights on the lid as they are quite strong aswell. I think they eat mainly crustations such as crabs and crayfish. They suck all the meat out of them and you are left with a perfect skeleton of the cray or crab.