There is no set rule on how many players must play each position on a U12 team. The only rules are that there must be a goalkeeper and a cretin number of players on the field.
It depends, most places 11 a side however, a few leagues change this but not often.
Strictly speaking, there should be 11 players, including the goalkeeper. However, because the Laws of the Game permit leagues and competitions to play small-sided for younger players, there are usually 8 players per team, including the goalkeeper, on the smaller fields.
I play U12 right now but I'm pretty sure that last year we played 8 on the field counting the gollie
There is no unified standard for youth field sizes.
No more than 11 per team. Different leagues will have different numbers based on the needs of the players. For example, a lot of recreational leagues will play with 8 per side to allow the players more touches on the ball. More in-game touches increases skill.
It would depend entirely on the league in question. Not more than 11.
it matters with age 11 v 11 is how it is played at the professional level (i think) but it is less when it's u12 I belive it is 11 players (including goalie).
Some countries use a full-size ball, but many recognize that U12 players might not be able to properly handle a full-size ball. Therefore, the USSF recommends that a Size 4 ball be used, which is about 2 inches smaller in circumference than a full-size (Size 5) ball.