I just finished an Authorize.net implementation myself Friday. I would recommend that you just remove/delete the select options for both SOLO and SWITCH in your checkout.php form.
As for test mode, you will want to stay in test mode in your Authorize.net login until you are sure that you have good communication between your website and Authorize.net. Once you're positive things are working correctly, you will need to edit the settings in your confirm.php page, specifically in your Local Checkout behavior to no longer run in test mode (change TRUE to FALSE for test mode) and upload the newly changed page to your website. Then you'll also need to change your setting inside your Authorize.net login from test mode to live.
At that point your online store will be running live.