so there will be 8 to 10 led/xbee units plus the central node at the house to control them.
The series 2 models act as either end devices, routers, or coordinators. There can only be one coordinator per network, no more and no less. There is no particular advantage of a device being an end device over being a router.
So, every node, except the coordinator should be a router, meaning that each one can send data and can forward data from other nodes farther away.
The cheaper radios don't do routing, and getting one of them to transmit up to a kilometer is a non-starter.