Setting up Wireless Connection with Specified Speed

I'm setting up a wireless connection for a standard size apartment. I am a computer consultant but this is my first experience in setting up a large wireless network. The apartment's area is 700×700. I plan to have a connection speed of 50-100Mbps from an access point connected from a local ISP, then set up a mesh network with EnGenius Dual Radio Access Point. I expect to only have at most 40 customers, and I could only provide simple internet speed ranging from 1-4Mbps. Looking at the available space of the apartment building, 11-12 access points will do and one for each building. I want to use only one hardwire which is the one connected to the first access point from the router, and then from the ISP. My questions are:

a) Is this a feasible plan or I could still build up a simpler and a cheaper one? Is it possible to use only one hardwiring?

b) Does anyone have used the EnGenius Outdoor Dual Radio Access Point before?

c) Is 100 feet too long for the average range of wireless devices?

d) Other companies create a dual radio outdoor access points, like Extreme Networks Altitude and Cisco Aironet for $1000, but is it justifiable versus a cheaper brand of access point like the EnGenius EOR7550 or EOA7535?

Thank you for your help.