You're going to have to put a single router in front of those wireless connections.
Nah, I'm just using them as-is, considering it's a temporary connection. I don't care if there are three networks in the building for now, it'll help spread the load anyway. Besides, I'm not sure how I'd do that, as these are modems/routers.
It's a new building? Did they tear down the whole block? Are there any neighbors left? If so, have you asked them what kind of internet access they have?
This is what has ended up pissing me off the most about Comcast. When we started everything, they told us there was service on our block (the rest of the block is not new, they just tore down a building right in the middle and built it back up). Sadly, it wasn't until after we found these problems that we went to the neighbors, who told us that they didn't get Comcast because they were told they couldn't get it. They all have DirecTV, and I'm not even sure what they do for internet. DSL, I was told, but I don't know how that's possible with this supposedly crushed conduit...