Hi,
Just start with one tower, but know that you wil have to add at least one or two more to become optimal results on al devices.
Hardware? hard to say, how many concurrent users will you approx. have? What's your available bandwidth? Do you think you have enough and accurate network/wireless knowledge to bring this to a good end?
Do you have a radius available for auth en accounting? Thought about billing yet?
Everybody wants to become a wisp, some of them become one, few of them survive
Reading your questions I think you simply don't have enough background to do this.
Hire a consultant or you will probably loose lots of money with zero results.
kind regards,
B
PS Please don't take this wrong, it's good advice.