So I am slowly getting closer to a successful transfer. I was able to import the tables okay, and just about everything worked (still have a few things to iron out).
I've now upgraded from 1.2.2 to 1.5.8 successfully, but now I get this error on the main forum:
Mysqli prepare error: Key 'last_post_date' doesn't exist in table 'thread'
- Zend_Db_Statement_Mysqli->_prepare() in Zend/Db/Statement.php at line 115
- Zend_Db_Statement->__construct() in Zend/Db/Adapter/Mysqli.php at line 381
- Zend_Db_Adapter_Mysqli->prepare() in Zend/Db/Adapter/Abstract.php at line 478
- Zend_Db_Adapter_Abstract->query() in XenForo/Model.php at line 219
- XenForo_Model->fetchAllKeyed() in XenForo/Model/Thread.php at line 563
- XenForo_Model_Thread->getThreads() in XenForo/ControllerPublic/Forum.php at line 104
- XenForo_ControllerPublic_Forum->actionIndex() in XenForo/FrontController.php at line 351
- XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 134
- XenForo_FrontController->run() in /home1/nintybuzz/public_html/forum/index.php at line 13