Sound massy, and with todays managed solutions overly complicated. A decent managed network and receivers will allow 100 connections per access point (with Ruckus anyway, not sure about the limits on the others) and zero config once you have configured the controller.
D-Link DAP-2590 access points. These are the same for factor as the current APs and would just drop in. Would give me the same coverage and wireless n but not sure if they will support the 30 clients per classroom I may need in the future.
Go for something like the Netgear WNAP210 and place one in each classroom – see the green dots on the map. This would give me wireless n and with the extra APs I could create 2 SSIDs and alternate them so that in theory each classroom could see both and then set up 2 trolleys to each SSID so if used at the same time each SSID would only have the 1 trolley connected.
All advice and suggestions welcome.