1

The upgrade would certainly fail, plus OpenCart would stop running. Config.php files include path definitions and required for OpenCart running. Upgrade wizard would try to retrieve directory information from config.php files but would fail since the files are empty. So, we should not forget to have backup of config.php files under our hands in a safe place.

2

It is false. OpenCart automatic upgrade script supports versions higher than 1.3.0. If we have an older version, we will need to first apply all upgrades individually until we reach to 1.3.0. Then, it is possible to apply the universal OpenCart upgrade script.