well my birthday is comming up soon and it will be my seventeenth (yay!!!

) and one of the things i would love to take up is riding (instead of driving a car like everbody else i know...i know lots of boring and unadventurous people). i know for my first bike it has to be 125cc or under until ive had my bike for two years.
so just a few questions i need answering...
1)do i need a car licence or just a normal provisional?
2)what bike is good for a new rider? (ive heard things about the 250R ninja being very good for new people but i would have to get it restricted which leads to my next question...)
3)is it worth me getting a high cc bike and restricting the power or just buying a second hand low power bike?
4)this is the most important question for me...is it worth it or should i just get a car???
thanks everyone.