Quote:
| mysql_connect(): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' |
The above error is not one that is specific to vBulletin, rather, the server you are hosting your vBulletin forum on. The error above is simply stating there was an error establishing a connection to the MySQL server.
When there are too many open connections on the server as a whole, MySQL may fail or crash, which would cause such an error to appear. While upgrading me help your forum, it most likely will not get rid of the error if the server you are on is overloaded or there are already too many open connections from other websites on the server.
You should most likely contact your host and ask them to increase the number of connections allowed for MySQL or, if the error persists, look into changing hosts.
I'm not sure how many members you have online at any given time, but if you only have a few, then I would look for an alternative.
As for editing your forum, the FORUMHOME templates control most of what index.php displays.