What do I request from the LAN upgrade contractor to avoid simple oversights?

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http://serverfault.com – The company for which I work have allowed me to hire a LAN wiring contractor to completely overhaul the building LAN. Currently there are old 10MBit Ethernet cables and switches running and I requested Gigabit LAN with a new power managing switch and wifi AP on each of the two floors. Currently there are about 10 computers on each floor. No server. We are switching to a cloud-based financing system, hence needing a good internet connection. We are also planning deployment of Google Apps as well as upgrading to a 20MBit downstream internet connection (currently 5MBit). I see Google Apps have (HowTos)