There isn't a clear answer on when.
Yes. Bicycle Motocross BMX
Bmx is a new sport for the 2008 Olympics
It got popular enough to be requested, and it fulfilled the requirements for an olympic sport, with national and international organization and competitions, so it got added to the list.
Yes. Several different versions even. Track, road, MTB, BMX.
Well, it's popular, it fulfils the requirements with national and international organizations and competitions.
Freestyle BMX is another name for BMX stunt riding . BMX is a special bicycle designed for doing stunts. There are 5 main disciplines in the BMX sport and they are trails, flatland, vert , street and park.
Yes, BMX bikes were used in the 2008 Beijing Olympic and is going to be used in the 2012 London Olympic.