If I'm building a new comp with a new case, do I need to purchase a separate printer port for it? Or is that method totally out of date. As well, do I need any other ports for an empty case (mouse, keyboard, sound...)?
Depends on the printer, but most consumer level printers nowadays are USB so you do not have to purchase anything for your new computer. If you are building a new computer, then all the ports that are necessary are on the back of the motherboard.
I have seen many printers for very specific situations that still use parallel. Usually for production companies or older ones for point of sale computers. But if you do not currently have a printer that requires parallel do not worry about it. And if it is for personal use,