AstroAI White Mini Fridge​ for Skincare, Bedroom, Office and Car, 4 Liter/6 Can, AC/DC, ETL Listed

No, this will only operate on 12v dc from a car cigarette lighter socket or 120v ac from a wall outlet.

Yes it locks very solidly. The latch is flush with the front of the fridge.

Yes you can definitely use an extension cord.

COOL TO WARM: Cool up to 32°F (0°C) below ambient temperature, or keep warm up to 150°F (66°C)，86°F (30°C) -64°F (18°C) within an hour, 86°F (30°C) -50°F (10°C) within 2 hours, 86°F (30°C)-37°F( 3°C) within 3 hours

It’s very quiet. This mini fridge has a 25 DB Sleep Mode.