It depends on your application. For a normal 2wd buggy/truck a 540 motor is fine and 60-80 amps will work fine (unless you are running a really low turn motor, then you might want to step up to a 120amp esc).

For a 4wd sct id go right for a 120a esc and a 550 motor or a 4 pole 540.

Geared correctly you shouldnt need a fan if you are just bashing around.