About 10-16 inches.
The distance is likely to be different depending on what State you live in. Where I work, in the State of Washington, the front wheels must be within 12 inches of the curb, and if on a hill, the front wheels must be turned in.
Usually 12 inches or less.
Not necessarily. In California your tires shouldn't be more than 18 inches from the curb or you could get a ticket. You can park as crooked as you want as long as both of your tires aren't more than 18 inches from the curb or edge of the road. If I remember correctly, that was the length of their baton so it was pretty easy for a law enforcement officer to check the distance. When parking on a hill, the goal in turning your front tires is to make the car roll OFF of the street and out of traffic if it starts rolling by itself.
From the Calfornia DMV web page on parking: When you park alongside a curb on a level street, the front and back wheels must be parallel and within 18 inches of the curb. Park parallel to the street if there is no curb.
In New Jersey, vehicles must be parked within 6 inches of the curb. Parking too far from the curb can result in a ticket, as it is considered a violation of state parking regulations. Always ensure your vehicle is parallel to the curb and not obstructing traffic.
One foot.
One foot.
When you do parallel parking you must align the wheels strictly parallel to the curb, and then shut the engine off.
Within no more than 30 centimeters.
Although it may vary from pace to place usually you must be within 12 in from the curb
12
In most cases, it is 12 inches or less. Some localities can actually ticket you if you are over 12" from the curb. In San Fransisco, if you fail to turn your front tires toward the curb, you can be ticketed because cars in San Fransisco can accidentally roll down the hill if the wheels are not angled.