1. Install with demo data
2. Try to add upgrade if possible.
3. Below link explains why we dont give upgrades to abantecart:
http://docs.abantecart.com/pages/upgrade/manual.html
(i.e. it need to modify dbprefix in upgrade.sql file provided in upgrade package)
4. Remove the INSERTS FROM `messages` table which states to delete the install directory
5. select mysqli
6. PHP REQUIREMENT LINK : http://docs.abantecart.com/pages/install/system_requirements.html# and also check index.php MIN_PHP_VERSION constant.