What type of network hub for Printer/Internet?

I have a friend who has a Mac Mini and currently has two LAN cables she needs to use. One is for a Ethernet printer. The other is for a Internet connection (Comcast Cable Internet). For now she is constantly switching between the two and wants stop doing that.
I suggested a network hub or switch but I'm wondering if it's as simple as that. If she purchases a hub or a switch if she simply connects to two cables into that will everything work fine? Any suggestions of a good but reasonably priced switch/hub?
As well, will any changes need to be made on the computer itself or will this be automatic when both are connected?
One last question: I know for home use I have a actual router but I have a home network and share the internet connection which she won't be using so I assume that is a router isn't necessary. Am I correct?
Thanks in advance for any help.

Yu're pretty much spot on with everything you said in your post. A hub or switch would be a really easy way to get everything taken care of without having to switch cables around all the time. I have one just for the same purposes that you posted above, and I have this one.

I don't know for sure if the connection will be automatic, but I think it will. It shouldn't be too much work to get it set up anyway.