Revolving refers to something that is going around something else. Rotating refers to something that is spinning in circles(typically around an axis) by itself.
3.) "The tilt of the Earth's rotation axis provides conditions for its climate to be suitable for life. By altering what portions of the Earth get the majority of incoming sunlight, no region on Earth is allowed to heat to extreme temperatures"(energyeducation.ca)
4.) I'd assume that there are more hours of daylight if Sydney is facing towards the sun. I'm not particularly sure why though. ¯\_(⊙_ʖ⊙)_/¯
