Number of parameters varies for different commodities, majorly the physical parameters are tested. For some commodities Oil content or chemical testing is also performed and then certification result is published on e-NAM.

Currently the assaying is conducted by the APMCs and they do not charge any fee from the sellers.

Yes. Farmers can sell their produce on e-NAM without assaying also, but in such a case he may or may not get the better price on e-NAM.