the LED's draw their power from the same wire that runs the fan itself.
easiest is going to be joining them together and run off a 4pin PSU connector.
rig up a switch after they are together and b4 the 4pin connector and then you can turn them off at will (will turn off the LED and the FAN)
you will not be able to control the speed this way (on full speed all the time)
The fans and light should shut off when the pc goes to sleep as the only thing running would be the 5v standby. I dont beleive mine fan led's turn off when the monitor goes to sleep and dont see how they could if they're attached to the motherbd, theres no seperate line for led control.