We sent out a custom email this week that I spent a long time coding in pure HTML/CSS. Is there any way of finding the code for the email so that I can use it as a template in the future? It seems as if once the email is sent, it is deleted?!?

This absolutely is possible! Just go to the Outbound Tab and find the email you sent. Simply edit the email and copy your code. You can add new email templates here.