Payment Processor Error 9003, and logging
Answering (2) only here.

CiviCRM's payment processor logs vary in their location based on the CMS in use. These logfiles include a unique string per site, as the logfiles are  located within the webroot and a hard to guess filename offers some defense against attackers viewing debug output.

This is documented @ -


https://wiki.civicrm.org/confluence/display/CRMDOC/Debugging+for+developers#Debuggingfordevelopers-Logfiles
https://wiki.civicrm.org/confluence/display/CRMDOC/CMS+Standard+Directories+and+File+locations 


WordPress

4.6 and below: wp-content/plugins/files/civicrm/ConfigAndLog/CiviCRM.HARDTOGUESS.log
4.7 and above: wp-content/uploads/civicrm/ConfigAndLog/CiviCRM.HARDTOGUESS.log

Joomla

media/com_civicrm/ConfigAndLog/CiviCRM.HARDTOGUESS.log (1) or
media/civicrm/ConfigAndLog/CiviCRM.HARDTOGUESS.log (2)

Drupal

sites/&lt;sitedir&gt;/files/civicrm/ConfigAndLog/CiviCRM.HARDTOGUESS.log