Lance has all the right answers here but I'll add to it.  Unless your sites are all in a line it is best to use multiple point-to-point links that a point to multiple points.  You will have better throughput to all the sites this way.  You will need to choose separate, not overlaping channels if you go this route for your access points.  If you use a Nanoswitch you many need to get a higher output power supply than the standard .5 amp version included with most radios.  I believe the bigger one is 1 amp.  I haven't built a long range link in a long time so I can't recommend any equipment but iI do know the AC versions of things are the way to go.