A door that large will catch wind easier when your opening and closing it. Unless you use real good hinges the extra weight may make them creak more
Windows can be as easy or as hard as you want.
One simple way to build them is to build a window sill with a ledge on the inside to keep the water out. Build a wood frame to fit on the outside of the blind and install glass or plexiglass. Drill a hole above the window and install a grommet. Tie a string to the front of the window and run it through the grommet, then tie a washer to the end of the string inside the blind. Install a screw on the inside of the blind to slip the washer over when the window is open.
When you sit down, you can pull the washer from the inside of the blind to open the window and slip the washer over the screw to hold the window open.
I have also just used a rail system and plexiglass to make sliding windows. I don't like them as much because half the window is always closed.