Some open ports, how to close them?

NIC is Network Interface Controller. But yes, you can drag a shortcut to your LAN connection on the desktop, then simply enable/disable with r-click. Actually, my suggestion would put the icon in the taskbar, but if you are more comfortable with it being on desktop, than fine. Functionality is the same.

It is a part of ICS (Internet Connection Sharing) that lets other clients on your shared connection control the router through SSDP and UPnP. Here's a good reference I found on it.
Since you are a single user behind a router, you have no ICS, so I recommend disabling Internet Gateway as per these instructions. It does not hurt to leave it as it is, but why have active something you don't use?

Regards,

 

Thanks for all answers.