1. thanks
2. I dont know what RotateAround(); is so I used Rotate(); and parented the planets to the sun, the problem with this is that the planet go at the same speed, that is not physic
3. for the spawning its
Instantiate( 1 , 2 , 3 );
the 1 is what to spawn (planet)
the 2 is where to spawn (the mouse position)
and 3 is condition I think, just put Quaternion.identity it will put it at the original rotation when you spawn