You can use a thermal pad, but the are not as good.
To clean the CPU and heatsink anything 90%+ alcohol will do, but 99% is better. You should get something like this in a chemist, but I have never tried.
You can use any thermal paste that you can find on a computer store. AS5 is the best though. And it is essential, as the surface of the CPU and Heatsink are not perfectly smooth. It may feel it, but there will be microscopic gaps inbetween, where air would be trapped, and this is not good, as it would act like a oven.
There are austrailian users here that know a good place to buy hardware. It was in a sticky all the good places, but they un stuck it.