I'm not sure how many, but the reptile keeper that told me this did say that it would be less than what was there before. The good news is that they will be "rare" (he did mention giant salamanders!) species according to the keeper.
The buildings (one main building and a smaller building) are going to be both one level.
According to the keeper, they should start construction on the reptile house by the end of the month.
I talked with a reptile keeper a couple weeks ago (late May 2011) about the overall exhibit set-up of the new LAIR. As mentioned there is a large building that will house an international collection of reptile and amphibian species, a small building that will showcase Southwestern species (US and Mexico) with a focus on rattlesnake species, and an outdoor exhibit for false gharials.
He said that the main building will have a large display of frog species from around the world. There apparently will be very little focus on invertebrates. The keeper was of the opinion that the inverts were mainly included in the title of the building so that they could give it the cool LAIR acronym. He said that there was little enthusiasm/expertise for inverts on their current staff and that people were burned out on spiders from their "Spider City" temporary exhibit in 2007. I found this somewhat disappointing as I was hoping that there would be a meaningful representative of at least some arthropods in the new building.