In your first sentence it is more natural to leave out the word "up." For the second sentence, I agree with Terry May. I would say "placed" instead of "laid" although it is not technically wrong. for the fifth sentence I would say either "stay down" or "stay seated." And the sixth sentence should be, "When you put your sweater 'backwards' it means that the rear part is on the front side." The eighth sentence should be either, "Do you want to come out of the shower?" or "Do you want to get out of the shower?" We say "out of" in both cases.