Hello,
We have a logo tutorial here:
http://www.shape5.com/documentation/Getting-Started/How-To-Change-The-Logo-in-JoomlaIf you want to change the name of the file, that's considered a customization and you'd have to modify the index.php file to do this. We use a module position in the logo area as well, for easy changes.
The phone number is a custom html module published to the custom_2 position.