Can't find my extension option under administer>System settings
The extensions need code files that are not in your database, but your imported database will have a table called civicrm_extension with a list of the installed extensions. 

So it will expect every extension in that table to be present (code files) in the correct spot. Obviously that is not the case. You need to either re-install these extensions OR also copy the extension directory from your source installation. Does that make sense?