Preserving Settings

I'm using G2 2.1. Nothing else is really relevant I don't think.

If I put all my relavent files in local directories, I'm under the assumnption that I can update G2 and not lose any formatting, including the siteadmin.tpl? I have the css file in it's own "local" directory and all of the theme's .tpl files in their local directory. Can I do the same with the admin.tpl thereby preserving all of my setting from admin and the ones I did manually to the tpl/css files?

Thanks