sojweb

As far as authors, you could just use a lot of the code from an author template. Have a look at these:
http://codex.wordpress.org/Author_Templates
http://codex.wordpress.org/Template_Tags/wp_list_authors

And when you say avatars, I’m assuming you mean gravatars? Once you get their e-mail address, you can generate the gravatar like so:

http://en.gravatar.com/site/implement/php

No, those are definitely PHP errors. It’s trying to load extensions it can’t find; it has nothing to do with WordPress. Looks like they might have re-configured PHP but used an old php.ini file.

When you e-mail them be sure to include these errors so that they can see what they are.

Something is wrong with your PHP installation or php.ini file. It’s trying to load extensions that are either not there or are corrupt. I’d alert your hosting provider.

I don’t quite understand what you’re trying to do; could you be a little clearer?

By blog page, you mean the page listing multiple posts? The function is probably not being used in the Loop, and $post isn’t referring to what you think it is. Take a look here, if you haven’t already:

http://codex.wordpress.org/Using_Custom_Fields#Getting_Custom_Fields

That function can give you detailed version information about the browser. There’s also a quick and dirty method, like this:

function is_IE() {
$pos = strpos($_SERVER['HTTP_USER_AGENT'],' MSIE ');
if($pos!==FALSE) return TRUE;
return FALSE;
}

If you have CPanel, you should have AWStats available… that’s a great general purpose log analyzer. You can see which files are being transferred the most and the top referring domains.

Have you looked at logs to see what’s eating up all the bandwidth? There could be something you could do to cut down on the bandwidth being used; maybe there are some images that aren’t compressed as well as they should be or something.