1. My apartment was Reddit HQ before we got bought. Where else would we have put the backups?
2. As best I can recall, the only thing on the web nodes was a source code checkout. I don't think that's particularly sensitive.
3. As ig1 notes, back then we had unencrypted passwords in the database and database copies on our machines, which were our personal laptops, so a spare drive in the apartment was the least of our problems.
When you ignore the CDN and other external resources, that's pretty much how most text based sites are. The ads alone probably exceed that 6.5TB number.
Also, be careful with those dedicated servers. They can give you ONE MEEELLION TB of bandwidth but it won't do you any good on a 100mb pipe or an extremely oversold network.
http://www.reddit.com/a2zte