Chuckie chicken
Chicken Chucker
Assuming the corrugated metal is a thick enough gauge, here's a pretty simple idea for windows. Cut a single piece of wall out, whatever size works best, and make a 2 x 6 frame covered in hardware cloth that fits inside the hole. Set your frame in the opening, then build a 2 x 2 frame around it on the outside of the wall flush with the 2 x 6. Push the assembly all the way in, then make the same 2 x 2 frame for the inside and push it tight to the inside wall so you've sandwiched the 2 x 6 securely between the two 2 x 2 frames and the wall of the shed. This should cover any edges of the hardware cloth for a neat finish, it will secure your window, and it will provide material at the top of the frame so you can hinge the cut out portion to use it as an awning to control airflow / snow flow / rain flow. You could also make shutters, which would be lighter, but they don't provide any overhang.