I have seen mixed evidence about hot water being more effective than cold water when washing. Do you have a reputable source?

Does the detergent not sterilize everything?

It doesn't sterilize, but it does bind to viruses and bacteria so they can be washed away. It's the reason why you don't need antibacterial hand soap: you don't need to kill, washing off is enough.

It doesn't. But drying in high temperature does.