1. It would have to be index.php, unless you change your server so that a .html file gets parsed for php.
2. The SQL you'll need:
Who's online:
SELECT name FROM accounts WHERE loggedin=1
Newest member:
SELECT value FROM settings WHERE setting='newestplayer'
Then
SELECT name FROM accounts WHERE acctid='$newest'
(where $newest is what was returned form the previous query)
Latest Hero (if the statue module is active)
SELECT value FROM module_settings WHERE setting='hero'
Then
SELECT name FROM accounts WHERE acctid='$hero'
(where $hero is what was returned form the previous query)
Total member count:
SELECT count(name) FROM accounts
You might have to change the table names if you have a prefix