South West State University installed a series of four Wi-Fi omnidirectional APs spread across the ceiling of the main floor of their library.

South West State University installed a series of four Wi-Fi omnidirectional APs spread across the ceiling of the main floor of their library. The main floor has several large, open areas plus two dozen small offices spread around the outside walls. The WLAN worked well for one semester, but now more students have laptops, smart phones, etc. and performance has deteriorated significantly. 

What would you recommend they do?  Additionally, there a recent concerns around security for the offices in the library. What would you suggest they do to handle these security issues?