Suggestions for a Greenhouse newbie

[3rdMaestro]

Hello all,
I'm considering constructing a small greenhouse in my backyard to move my collection into, a 6x6 or smaller. I plan to fill it more or less with tolumnia, and the stray phals that people keep gifting me. Since I'm new to this and still in design stage, I was looking for suggestions.
1. Tolumnia love air movement. I guess that means I need fans? Will any plain old fan do?
2. How does one control the amount of light? The place I was considering putting it has a shadow from the house begin to creep over the area after midday.
3. I'm not worried about the cold. I'm worried about the ridiculous summer heat. What can be done to fight the heat?
4.... Am I missing anything else?