move

Introduction
At the moment, there is a static website at foobar.example.com. I want to use Drupal (multi-site) to build a new site at this domain. But until it is finished, the static website shall stay.

Is it possible?
Can I create a multi-site at foobar2.example.com, build the site, and later rename the folder inside of sites from foobar2.example.com to foobar.example.com and change $base_url inside of the settings.php to the new domain? Anything else?

In my multi-site setup, I want to install only "finished" releases (so: no dev version, no beta, etc.) to /sites/all/modules.

So when I install a dev version to my multi-site /sites/example.com/modules, and this module will get a release later, I want to move it to /sites/all/modules.

Does this work without any problems? Anything to mind?

Would I need to update the module at the multi-site first, before deleting it and re-install it in /sites/all/modules?