What is the percentage of making it into the MLB?

Impossible to tell as it really depends on how good you are ?
My percentage would be less than the chance of winning a quad roll over Euro draw, so about 0.0000000000000001%

Depends on how good you are

Are you on a team, if your on a college/university team you have better chances than a high school team and if your not on any team, I would say about 0