No it is not a modem. You may have this solved by now, but it is just a device to give you more LAN ports. If your incoming Internet connection is an Ethernet cable, you don’t actually need a modem.
Personally, I would go with option B. Then you can still monitor the activity and the firewalls in your router are still protecting whatever you end up plugging into the switch.
This is a switch which can add ports to a router. Typically you need a router to connect to your cable/internet. Then add a switch to add extra hardwired ports. There are “managed switches” that can allocate IP numbers to your network devices. But it’s simpler to connect a switch to a WiFi router to add more hardwired connections to your wired/wireless network.
This is NOT a router. It's used to connect other devices to your router. You plug your devices into this switch and then plug this switch into your router to connect the devices to your network and the internet.
This is a switch. Think of a switch like roads in your town. It gets you around your small area, but will never leave that area. A router is like a highway that takes you to a new area. This will not replace your router. Netgear has some good routers, but just make sure it has router in the description. Another thing to consider is your internet type. Your old.router may have been a modem built in as well. Check that to make sure before buying a new one.
This is what you need to supply internet to more than 1 device IF you also have a router. (most providers have a router built into the modem). This does not supply any wifi signal. (you would need an access point for that)
I had the 4 output option & upgraded to the 5 port , runs smoothly for my use of streaming with out glitches or snags. Would think it work for your needs/ run 5 G thru my home.
It is not. It only provides enough power to run the switch and to send and receive signals from your device. You'll still need to power the device another way. However, it is still a great choice since this design has stood the test of time for decades.