Can I import contacts directly into a List?

Contacts can be imported directly into a List by following these steps : 

Login > Marketing Tools > Overview > Contacts > All Lists                   

On this page all the Lists are displayed, click on the "Manage" button next to the particular list and select Import Contacts.

A new page will open up with the option of Manual Import (where you can type in the specific email ids) or CSV Import (allows you to upload a CSV file).