We very rarely approve requests for the advanced version of PHP because it creates security flaws. Intermediate should be fine.
If you feel you need advanced, post your reason here.
1) DNS is managed by a different server so it doesn't matter if it's offline.
2) I have notified the administrators regarding the load.
3) Most likely related to the load.
Your site is loading for me. Try flushing your DNS cache.
http://www.tech-faq.com/flush-dns.shtml
DNS is run by a different server so it doesn't matter if it's down.
Regarding the login problem, get rid of the chat/ in all the xmlHttp.open lines in the file scripts.js.
It does not matter if DNS is down as it's managed by a different server.
The IP address is shared between all users of the server.