There is no definitive scientific answer for why tortoises poop in water. One answer is that warm water relaxes a tortoise’s bowels making it easy to release poop. Another possibility is a “hygiene mechanism” in the wild (poop in running water and bye-bye poop!)
What to do if your tortoise if foaming at the mouth: Immediately check the temperature in their enclosure and basking area and correct as needed, Separate out the sick tortoise if there are others, Keep her and her home clean, Check if she’s eating (a healthy appetite is a great sign), Talk to a vet as soon as possible.
There is no specific amount of time that tortoises need to exercise. But during the waking summer months, it is good to have your tortoise exercise for at least one hour a day. Try to encourage walking, gentle climbing, and some digging. During the colder months the waking hours for tortoises are reduced significantly (or completely, if hibernating) so exercise will naturally be less.
If your tortoise went missing, here is how and where to go look for them: look for burrows, look under things, inside anything they can crawl into, wait for the morning sun as it might bring the tortoise out of hiding, and alert the neighbors. If all else fails alert relevant authorities in your area, and advertise on Facebook or in your local paper.
Tortoises and hedgehogs are unlikely to live together comfortably. Tortoises are generally solitary creatures. Hedgehogs are more social, but they could be at risk from the salmonella that many tortoises carry. Overall, the environments that these two animals require are quite different so it’s a real challenge for a tortoise and a hedgehog to live together.