As far as I can tell:
1. In manual focus mode the camera focuses in the center of the frame, and displays it in that magnified area to make it easier to see when the focus is achieved. If you want to focus on a certain object you'll need to move the camera such that the object isvisible in the magnified area. You can reframe afterwards to get a different composition.
2. You cannot change the amount of time the magnified area is displayed. You'll need to push the joystick as for refocusing to bring it back on the screen.