XQuartz X11 2.7.5 not found
If you go to the XQuartz home page you will find a link to download XQuartz that should be correct.

If you are running OS X 10.9 then you need version 2.7.5

At the moment it is http://xquartz.macosforge.org/downloads/SL/XQuartz-2.7.5.dmg but our friends at MacOSforge appear to have a broken server. The problem is not yours, it is on their system.

Wait a few more hours and it should be right.

If you can't wait then grab it from my dropbox :-

https://www.dropbox.com/s/m6c2owdu0nkf7aa/XQuartz-2.7.5.dmg

(note to everyone - I'll remove it in a day or so. Try the website first.)