Key_Master - 8:55 pm on Jul 9, 2013 (gmt 0)
Content-Type is standards but it must be properly constructed. Make sure it doesn't end with two newlines. It should end with one newline.
302's are temporary so I don't see the value in using Vary or Set-Cookie on them if you can help it. It the page that the 302 redirects is directly visited by a user agent (without following a redirect) it will not know about a Vary or Set-Cookie header.