6. Many of the new nozzles are made of plastic or ceramic. As they are comparable to steel in terms of wear and tear?

There are many different types of plastic used for manufacturing the nozzles. They wear out not earlier than steel, and sometimes later. However, the cleaning should be done with caution, as irreversible deformation may occur. Ceramics - the most resistant to wear material, it can be operated 10 times longer than steel.