Yes, in the paper tray or feeder.

In principle, yes; however, I recommend that you buy an additional shaft (is simply mounted underneath).

The two bottom trays are adjustable. Adjust the size using the sliders and indicate the paper size at the front of the tray.

Yes, you can. You simply have to set the inner guides to A3 and select A3 on the side of the dial. This allows you to use a wide range of paper formats, from A5 lengthwise or crosswise to A4 and A3.