How to change tabs to standard horizontal navigation?

Do you mean putting those links in the sidebars? You can disable Primary Links on the theme settings page (handbook: http://drupal.org/node/357261) and use the menu blocks in your sidebars.

My understanding is that you want the tabs floated left instead of right - i.e., left to right

You can do this by adding the following to local.css (please see the local_sample.css file that came w/ the theme):

#primary-menu 
  float: left;
}