CRM-10358 separate payment No thank you to notice errors, spurious additional contribution

Running r40945:
If a contribution page is configured to process separate payment for contribution and membership, and other amounts are enabled, then one selects no thank you for contribution, on save one sees the following errors:

Notice: Undefined offset: 1 in CRM_Contribute_Form_Contribution_Main->postProcess() (line 1210 of /Users/josephmurray/Sites/drupal-7.14/sites/all/modules/civicrm/CRM/Contribute/Form/Contribution/Main.php).
Notice: Undefined offset: 1 in CRM_Contribute_Form_Contribution_Main->postProcess() (line 1211 of /Users/josephmurray/Sites/drupal-7.14/sites/all/modules/civicrm/CRM/Contribute/Form/Contribution/Main.php).
Notice: Undefined offset: 1 in CRM_Contribute_Form_Contribution_Main->postProcess() (line 1212 of /Users/josephmurray/Sites/drupal-7.14/sites/all/modules/civicrm/CRM/Contribute/Form/Contribution/Main.php).
Notice: Undefined offset: 1 in CRM_Contribute_Form_Contribution_Main->postProcess() (line 1213 of /Users/josephmurray/Sites/drupal-7.14/sites/all/modules/civicrm/CRM/Contribute/Form/Contribution/Main.php).
Notice: Undefined offset: 1 in CRM_Contribute_Form_Contribution_Main->postProcess() (line 1214 of /Users/josephmurray/Sites/drupal-7.14/sites/all/modules/civicrm/CRM/Contribute/Form/Contribution/Main.php).
Notice: Undefined index: amount_other in CRM_Contribute_Form_Contribution_Main->computeAmount() (line 1151 of /Users/josephmurray/Sites/drupal-7.14/sites/all/modules/civicrm/CRM/Contribute/Form/Contribution/Main.php).

In addition, there is a problem with the cost of the membership being used as an additional contribution amount despite having clicked on No Thank You for donation - see images.