1) You can add it in the <head></head> of the email. Don't forget to add the "type" for your style tag like <style type="text/css">. Two media queries are used mostly for emails. For the email styling overall, give it without any media query. You can use @media (max-width:650px) and @media (max-width:400px) for styling purposes. Many Outlook versions doesn't take styling so don't forget to give inline styling for the elements.
2) Yes. It does. Especially for gmail (most devices).
If you were to add media queries you would have to do so in the email head because you can't attach a style sheet. That being said, check out this post about media queries support in email clients.
