What does the amps have to do with how big/powerful of a motor can i use? looking at getting new brushless esc and brushless motor to put in 1/10 rc buggy and do i need a cooling fan? thanks!

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.

My understanding is that your esc should be able to provide at least as much as your motor can ask for.
If you get a 120a esc and you have a motor that can take up to 180a, you are not taking full advantage of the motors capabilities. But you are not going to damage anything either.

You do want to get a lipo that can supply more power than your esc/motor combo can ask for. Thats another subject though.

Thanks!!!!!!!!!!!

I don't think this is entirely correct. If you have too hot a motor it will try and pull more amps than your esc is capable of supplying damaging it.

You are correct on the batteries though! Get a higher C than you think you need.

That's true, with planes that I have you want more esc capability than the motor. You reminded me of that now that I thought about it. Matched amp capabilities was not good. More esc amps than motor, better.