No - this will void the products warranty and may create a permanent damage. Only use power supply provided by Chip PC for that purpose (sold separately).
Yes you can - only the one supplied by Chip PC. We do not recommend the use of this converter unless you are forced to use legacy barcode readers or other non-standard equipment. If you need it just for keyboard and mouse - it is easier today to purchase new USB devices.
Yes. Legacy Barcode readers with PS/2 supported through special USB to PS/2 converter. USB Barcode readers are supported natively. Serial readers are supported by supplied USB to Serial converter.