A:Answer Yes. This is also a router, so you won't need the Spectrum router. If you are paying rent on it, I recommend that you return it. You will only need the modem.
This only has 1 LAN port. If you have more than 1 hardwired ethernet device, you will need an ethernet switch. If you are not paying rent for your router, you may be able to convert it to a switch, but not all devices can be configured like that. Ethernet switches are cheap - you can get them for around $15.