MyBB Community Forums

How hard would it be to change index.php to something like forumsindex.php? Would it be a matter of just renaming the index file or are there a million changes througout mybb that would need to be made?

Another question about the index. Could someone explain to me why, when typing in a simple address, the page won't automatically go to the index? i.e. www.mysite.com/forum will tell me the page doesn't exist. I have to type www.mysite.com/forum/index.php Why is that??

You can rename the file, but there are references to index.php in the templates (links and such) which you may want to change. There is a search (and replace) feature in the templates manager to do this.

Your server is probably not configured to have index.php as one of the default files to load. See:
http://en.wikipedia.org/wiki/Webserver_directory_index
http://httpd.apache.org/docs/2.0/mod/mod_dir.html
The Change Your Default Home Page section of http://www.hostingmanual.net/other/htfun.shtml