Answer to Question 1
Saturn's rings can't be leftover material from the formation of Saturn. The rings are made of ice particles, and the planet would have been so hot when it formed that it would have vaporized and driven away any icy material. Rather, the rings must be debris from collisions between Saturn's icy Moons and passing comets or asteroids. Impacts large enough to scatter ice throughout the Saturn system are estimated to occur every 100 million years or so. The ice would quickly settle into the equatorial plane, and some would become trapped in rings.
Answer to Question 2
The activity you see in the Galilean moons must be driven by energy flowing outward, yet these objects are too small to have remained hot from the time of their formation. Io's volcanism seems to be driven by tidal heating. Io follows a slightly elliptical orbit caused by its interactions with the other moons. As Io's distance from Jupiter varies, the planet's gravitational field flexes the moon with varying tidal force, and the resulting friction heats Io's interior. That heat flowing outward causes the volcanism.
Saturn as Seen from Earth
Saturn’s Diverse Moons
Francisco Goya, Saturn Devouring One of His Sons.
Permanent Gases of the Atmosphere
Coral growth rings as an indicator of environmental change
Deciduous and permanent teeth