I'm new to the forum (and chickens), but I raised hookbills for 15 years. Parakeets do pretty well in an outdoor colony situation, as long as you provide some warmth in the coldest of winters. Just make sure you have more nest boxes than hens and can protect food and nestboxes from the weather.
As far as a roof in concerned, I think it's important that the birds have some area of their flight to be able to get out in the sunshine and the rain. It makes a HUGE difference in their feather condition and over-all well being. I also made sure that all of my birds had a wind-protected section, although most will go into their nestboxes in the harsh weather. My flight cages were long and narrow, going from nest box, to wind prtection, to covered area, to comppletely open area.
I used to stand at my kitchen window and watch my birds showering in the rain.....so cute!! And a macaw showering in the rain is impressive, with their huge wing span displayed!!!!
Sorry I don't have any pics..... those days are LONG gone!! LOL