WAN vs LAN Ports – Difference Between WAN and LAN Ports

I would use ESW card in router if I had small office that needs to have 5 users connected. Then I would have router and switch in same device instead of buying a separate 2960 or such.

The only benefit I see with using EHWIC card would be if you need to use LAN features like port security, private VLAN, DHCP snooping etc. However in the first case you mentioned you would use the router as pure router and leave switching features for a real switch.

So it boils down to if you want to have routing/switching in one device or multiple. The only real use case I see for it is small office that doesn't need 24-p switch. You would only need to manage one device as well.

In your case, you don't need a router. The most common reason for having one is to convert from one kind of network media to another. Your ISP may use DOCSIS (cable), DSL, T1, or something else to connect you to the Internet, while your internal media is Ethernet. In your particular case, since your ISP provides an Ethernet handoff, you don't need a router.