confused with multi-language database setup.

I got it to work, multiple times, but in different ways. what i want is to run

www.mysite.com and have the same site in chinese,
cn.mysite.com

The first time, I set all that up in locale, languages & such, using http://drupal-translation.com/content/setup-multilingual-site as a guide (a very good one too!) and I simply used the SAME settings.php file for cn.mysite.com. However, I couldn't differentiate the theme (obviously because it's drawing off the same database info.)

The thing is, I'm not sure how the database is supposed to be set up. All I want really is to have a different theme for each language, as well as different logos. Nothing too fancy, though I'm looking to add a few things to the Chinese one to appeal to that market.

Current database setup is this for the main site:

$db_url = 'mysqli://dbuser:pass@localhost/maindatabase';
$db_prefix = array(
'default' => '',
'authmap' => 'shared.',
'permission' => 'shared.',
'profile_fields' => 'shared.',
'profile_values' => 'shared.',
'role' => 'shared.',
'sessions' => 'shared.',
'users' => 'shared.',
);

For the Chinese site, I have in /sites/cn.mysite.com:

$db_url = 'mysqli://dbuser:pass@localhost/cndatabase';
$db_prefix = array(
'default' => '',
'authmap' => 'shared.',
'permission' => 'shared.',
'profile_fields' => 'shared.',
'profile_values' => 'shared.',
'role' => 'shared.',
'sessions' => 'shared.',
'users' => 'shared.',
);

I'm thinking I'm looking at this language multisite wrong. This set up worked fine for another multisite I did awhile back, but that was only for English.

Should I be installing Drupal, then simply copy the same settings.php file from sites/default to sites/cn.mysite.com? Or should I be sharing some of the localization db's as well? Or should I only be sharing something to do with themes?