By Default, how many Product Tax Classes are included by Magento?

Suppose you want to effect changes to multiple products listed under Manage Products. You select the products and choose an action from the Action dropdown list. Which of the following are NOT valid actions?

Correct way to enter multiple keywords in the 'Default Keywords' field (marked as A in the image), while configuring the HTML Head Settings under the System > Configuration tab in the Magento backend?

Which property values must be supplied when creating a new Attribute Set in Magento?

Which must be selected from the 'Current Configuration Scope' if you want to import the Table Rates in Magento?

How many orders does each unique shipping address contain?

Which is not a Magento cache type?

Which is not TRUE?

Difference between Mage::getSingleton() and Mage::getModel() in Magento?

Dependencies between the modules of the application layer should be built only by the service contract or the service provider interface (SPI).

If module A declares a dependency upon Module B, which is not valid to declare such dependency?