res (red eared sliders) can go along time under water;don't worry about it just make sure they have a nice spot to reach and get air.
They can sleep for as long as they want some like to sleep on their rock while some like to sleep underwater both of my sliders love to sleep underwater.
They are reptiles... indefinitely, but they will become dehydrated after a certain amount of time. RES generally need to be submersed under water to drink and eat.
well they are aquatic so they will probably drink water from the tank
Sure, they do it in the wild. If you have pet red eared sliders and geese then as long as the geese don't pick on the the turtles you will be fine.
They dig a hole in the mud with their long claws
Yes, as long as they can fit in their mouth.
they wont live very long cause they get dry so fast so about one hour
Baby red-eared sliders... well for starters, don't worry about them drowning underwater. Just give them enough water so that their head is above the water. As long as they have some rocks on the side so that they can bask, you're good. =) Source: experience
Red-eared sliders don't need to stay with their mothers past egg stage.
in captivity 20 to 40 years with great care