All of them!
The most popular are Baseball, Basketball, and (American) football. Many kids play soccer (aka European football) but this is largely considered a child's game, and few people play competitively after age 10 or so. Ice Hockey has niche popularity, but mostly in the northern states. This question is kind of nebulous but hopefully this will be helpful.
depends on the sports drink
No, not all sports stars have sponsorships. Generally the elite athletes, which corporations think would be a good selling tool, are the only athletes who get sponsorships.
athletes that aren't very good.
striving hard to get high grades
Any country that has athletes that are good enough to compete in Olympic sports.
SPORTS for Exceptional Athletes was created in 2007.
Athletes
Yes and for the fun of it considering they are Amateur athletes and do not get payed.
The ones on France more than likely speak it.
No, they do not.
No
Both amateur and professional athletes go to sports clinics. Additionally non- athletes with athletic impairing conditions also go.