Yes, you can put soup into Chilly's Bottles. We recommend a really thorough clean straight after use with hot soapy water. For further cleaning please use bicarbonate soda with water.
Heat retention for soup will vary significantly based on the temperature of the soup.
We do advise caution not to leave any organic/food products such as soup that can spoil in the bottle for too long as this may cause pressure to build and potentially damage the bottle and lid.