i don't think you need to worry about gett the same rating fan. as long as it's 12v that's all that matters. unless there's some type of power supply in the cooler or something.

as for direction of fan. the wires can hook up either way. the fan will still work. just in opposite direction. it's not gonna blow.

radiator fan out of a car, or even the fuel pump. or a simple light bulb. they all work whatever way the polarity. just the opposite direction. cept the light. it lights up either way.