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.
Heat retention for soup will vary significantly based on the temperature of the soup.
We do advise caution not to leave any organic/food produce such as soup that can become spoilt in the bottle for too long as this may cause pressure to build up and potentially damage the bottle and cause lid failure.