This information would be told on the manual, or user guide.

Have you seen the notes of the 1.9.x firmware? Copy that for you: "As we have changed the saved config file format, then the config file of the old firmware cannot be restored to the new firmware. So...

Could only add port one by one...Same on the cisco devices.

I only know the public MIB and private MIB...

A simplest way: Set a password only you know...It looks like the Access Security could get a upper level control, you could have a try.

I found the SG3216 support 10240 Bytes jumbo frame, 9k frame will not be a problem.