I would like to retrieve the 'Minimum order amount' value for free shipping in the 'CartController.php' class.
How can I get this value? Would Mage::getStoreConfig() do the job? But which path?
the values are stored in the core_config_data table, and a search WHERE path like '%minimum%' should result in few enough rows for you to spot which one. Alternatively, the 'name' of the input-field in the admin area will be the path with _s in place of /s.