Here is some basic rules for a goalkeeper
According to FIFA's Laws of the Game, a goalie must wear a different color uniform that distinguishes you from the rest of your team, as well as the opposing team and referees. Just like field players, goalies must wear appropriate stockings, shin guards and soccer cleats. Jewelry is not allowed.
As a goalkeeper, you are allowed to handle the ball with your hands within your penalty area. You can catch any ball that is shot, headed or passed by the opposing team within this area. You also can handle the ball after it has touched one of your teammates, as long as the ball was not deliberately passed to you. In some cases, it is unclear if the ball is passed, at which point the referee makes a judgment call. If a teammate passes the ball, you must dribble the ball first and gain control. Only thereafter can you pick up the ball. You may not handle a ball from a teammate's throw-in; but a ball that is headed to you by a teammate can be handled. You can distribute the ball back into play after gaining control of it by throwing or kicking it. If you throw the ball and it remains in the penalty area, you cannot handle the ball again. You have six seconds to distribute the ball from the moment you gain control. If you deliberately take more time, you may receive a verbal warning from the referee and a yellow card caution on subsequent infractions.
Answer to your second question
Goal Keeper should remain on the goal line until the kick taker touches the ball.