If I created a webpage with a custom font and used it, would the visitor have to install that font, or would it be embedded (so the visitor doesn't need to install anything)?
If you used a custom font, you have to import it because if a visitor doesn't have a font in their OS it will be replaced with one of the default fonts
Here is some information of how to import fonts to your web page
Here you can find a little information about using google web fonts