Both are valid questions - rinse till the water runs clear, some sand seems to take forever but it's well worth cleaning it BEFORE it goes in the tank as fighting the clouds water later is a real pain. As for cleaning it, it's actually easier then gravel, you will develop a feel for how close to the sand to suction with the python, dirty material usually does not penetrate the surface of the sand so your tank stays cleaner with your vaccuming then with gravel. You do need to stir the sand periodically with a chopstick or something to release air posckets under the sand that can develop and become toxic. Once you try sand you will find that you love it and if you keep cory cats they will never be able to thank you enough!!!
ALASKA