It gets pretty hot. In the middle of the summer you are talking an easy 95 degrees. It's worth it though.
Its hit or miss, sometimes its busy and other times its dead. Either way, the place is huge so you don't need to worry.
I think its right about 5,000FT. Let me know when you plan your trip and I'll come out. I live about 90 minutes from the mountain.
-Zach