To hide, you simply have to go down twice and a button with a person will appear, where the fly swatter/spray appears; it took me a while to figure it out at first too.
For the Cooking minigame, they've included a video below. To change Yuna's positions, you have to press in the center of her body; "Shift Body" will appear there. The same applies to her arms and legs.
Just try experimenting and tapping. If you lose, you can restart the night without any problems. You can also read the game's wiki; they've included the link below.