My father was a jockey, then a trainer, I started riding on ponies then on horses almost everyday at 4 years old. I had to wait to be 14 to enter to the jockey school. I like to say that I was a born in a stall. I was more in the stabbles than in school.
To start working on racetracks, you may have to approach the institution handling races in your country. For example, in France, we have France Galop. Or you can ask the racetracks directly, they are often looking for volunteers on little racetracks in the country side.
I don't know anything about bets. I know that there's a win, place, show...
Don't ask me to bet, I don't know how to do it ;-)
I sometimes play with my friends to add some fun to a day but that's it. I understand that people likes to play, it's thrilling!