second router

so we have no service in out back to rooms about 200-300 feet from the modem/router.

I have a netgear cm700 and a netgear r7000

it looks like the cm700 is approved but not the r7000.

First question can I buy a Netgear WNR 1000 and use the cm700 modem and this router for my service?

Second since I don't get servise in the back room can I run the ethernet to the back and plug it into a router 

and have the second router for the back rooms.

Thank you