Nothing beats good old bleach! This is the gold standard for sanitizing anything bio-hazardous. Just make sure to rinse and rinse some more, since bleach is also quite caustic. The disposable Al trays are a good idea, too. The white spots, however, are more alarming. If they are ringworm, your vet may prescribe high dose Program for ALL your cats; to knock it out of Starr, and to prevent it in the others. I had to do this two years ago; it worked a treat.

Good luck!