The motors have ratings on them. The typical voltage for small scale is about 11.1 volts. There are many batteries with this voltage. The other factor to take into consideration is mah. This is has much current the battery can push out. The higher the number the more current available, however the battey also gets physically bigger and heavier.

Motor and ESC do not have to be the same manufacturer. The ESC should exceed the motor full load current rating. ( motor with 19A FLA need 20A - 30A ESC )

Remember each brushless motor will need it's own esc.

Brand does not really matter if this is a school experiment. Go with the cheaper MYSTERY or RC SMART should be ok.

Again try your local hooby shop and grab some magazines. Some hobby shops carry back issues for really cheap.