Yes, our solar lights are made with IP65 for outdoor use, they can work normally in rain, but not be soaking.
Yes. It is necessary to replace the solar light batteries 1-2 years after, or when you find the lasting time of the solar lights gets much shorter than before, you should consider changing new batteries in the solar light.
The solar lights can be automatically turn off when dawn comes. They have a lighting sensing control system and can auto on/off when sensing darkness/brightness.
Yes, the solar lights can be charged on cloudy days but probably not fully charged in a day, it can still use the stored energy from the batteries and light on at night.
Normally, the batteries in solar lights can last about 2-3 years before replacement needed. LEDs, the solar panels can last 10 years or more.