The broken white lines down the middle of the road serves as the separate lines of traffic or to protect any traffic that may be turning right.
yes
yes
yes
In California, solid white lines mark traffic lanes going in the same direction, such as one-way streets.
White lines mark the edges of roadways. They keep or are intended to keep people in "a lane" and off of the shoulder or from running off the road.
No only in a emergency
Yellow line while driving means the other sides traffic is opposite from yours. White line means same direction.
In the US, both solid white lines and double white lines are used to mark areas of prohibited lane changes in multi-lane traffic. Broken (dashed) yellow lines, solid yellow lines, and double yellow lines are used to separate traffic moving in opposite directions.
If you're asking in reference to America, the broken white lines are typically seen on any multiple lane road, highway, and freeway. These lines separate traffic lanes, going in a single direction on either side. It's okay to cross between lanes so long as the line is not solid, as many times as you like using proper signaling. Happy safe driving...
Vehicle traffic lanes
Vehicle Traffic Lanes