Yes, here is an example of what the 300 or 1200mA does for you. The voltage is 9 and that won't change. The mA is the demand you put on that voltage. If you have a spot light that needs 1200mA and...
It depends on the equipment being powered. Some devices will handle the additional voltage without any problem while others may be damaged beyond repair if 9V is supplied instead of 6V. If you are...
