As for their humidity problem, the article says little about how their badly designed chiller-less system got into a condensing situation. The original article in the Register does.[1]
This was an HVAC configuration error. The facility used evaporative cooling, which dumps heat into water by running air through a water spray or some wet surface. This raises the humidity. They somehow got the system configured so that it was recirculating air through the evaporative cooler, increasing the humidity on each pass until it hit saturation. The problem only lasted for a few hours until somebody figured out what was wrong.
They probably didn't have a union-trained stationary engineer on site. This sort of thing is covered in the apprenticeship training for a stationary engineer. Fans, dampers, and controls can all fail, which can create situations like this. Stationary engineers deal with those problems. At large data center scale, you may need one.
[1] http://www.theregister.co.uk/2013/06/08/facebook_cloud_versu...