I think I've spotted it

.
First of all I'd like to point out for anyone following this thread, that when installing using the Windows or Linux installation wizards, you shouldn't even have to edit the properties file since it is all done by the installer which even checks the DB connection and populates the tables.
When installing using the zip package (useful for where the installer isn't supported or for where you require a servlet engine other than Tomcat) you should follow the instructions in
http://www.konakart.com/installationfaq.php#Defining_Database_Parameters . Especially where it says :
<snip>
Leave the torque.database.default equal to oscommerce.
You need to set the five parameters appropriate for your environment:
torque.database.oscommerce.adapter (either "mysql", "oracle", "db2net", "mssql" "postgresql")
torque.dsfactory.oscommerce.connection.driver (All JDBC drivers for the supported databases are on the default classpath)
torque.dsfactory.oscommerce.connection.url (keep the value on the same line after the equals sign)
torque.dsfactory.oscommerce.connection.user
torque.dsfactory.oscommerce.connection.password
</snip>
In your case, you have changed torque.database.default which should have been left set to oscommerce and you have converted torque.dsfactory.oscommerce to torque.dsfactory.mydatabase in many places. Please try again just setting the five parameters above and I'm confident that it should work.
Let me know !
-Paolo