what exactly is electronic speed control?

It's the device that regulates the supply of power from the battery to the motor, based on inputs from the radio set. In other words, it understands when you pull the trigger to accelerate, and supplies more power to the motor, making it go faster... Its an essential component in an electric car.

An esc is better than an msc because an esc pulses power to the motor very quickly which uses up only as much energy as you want, an msc changes speed by running power through resistors which suck up a lot of power. It was always explained to me that with an msc your runtimes will be the same no matter how fast your going, and that that runtime is equal to going full throttle constantly with an esc. Not sure if thats exactly true but it explains the concept.

Is there a way to get more cooling to the ESC ore is the heat sinkĀ“s all there is as my emaxx have a tendansy to get pretty hot!
not att any danger levels but anyway. dont want to frie another one as they are expensive litle succers......lol

You could cut some holes in your windshield or buy a [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXKKN0&P=7]fan.[/link] That fan runs of 5 volts so you can plug it into your receiver.