Hi @rdevine,
1, 2, 3 look fine to me.\
On:
The controller that will receive the information will be a Raspberry Pi 2.0 Model B 512MB.
On the controller I am uncertain as to the software that will be placed on the controller.
There is some debat about terminology but I think most people on this forum agree that the controller is something like Vera, OpenHAB, DomotiGa, PiDome etc. For the whole list (answer to #5), see all entries under Select Controller. Many of these controllers can run on your Raspberry.
Between the controller and the sensors is the gateway, see under Select Gateway. Before you ask why the Raspberry can not be a gateway, see Port of MySensors Library 1.4 to Raspberry or do a search for Raspberry but for sure a Arduino gateway will be the simplest.