Hi Donna,
First of all I think you have a lovely space to grow quite a variety of orchids; that you can adapt to their different needs by shading, ventilation, or enclosing it. However the greenhouse of course is the ultimate orchid growers' dream, but what you have already is close to a greenhouse.
With regards to 'killing the orchids' I think you have to be careful, as actually it's harder to kill an orchid than any other plant! Your mistakes are only minor, and most orchids have a resting time and may appear dead for an amount of time if they are a bit dehydrated. As a piece of advice do not discard of any orchid if you are not sure, leave them on the dry side, but with a bit of ambient humidity and in a partly shaded spot, and they might come back to life for you...Good Luck!