Rules in World Cup Jam

LET'S JAM!

Can I participate in the competition if I am under the age of 18 and how many people can participate in a team?

While the theme is already released, why there is a starting date?

All jam info is already there, so what holds jammers to start from now?

Is this jam only open to residents of US?

Do I need to be an adult necessarily to enter the jam?