A baserunner on 1st is not forced unless the batter hits a ground ball, a base hit on a fielding error (he is also forced to advance on a walk, hit batter, catcher interference, etc.). The runner is not forced on a fly ball unless it is dropped or falls in for a hit. If a fly ball is caught, the runner is not forced, but may choose to "tag up" and try to advance to 2nd after the catch. If a fly ball is dropped, the runner need not tag up before advancing to 2nd. THEY CAN RISK IT...BUT IF THE BALL IS CAUGHT HE HAS TO GET BACK TO FIRST BASE.....OR IT WILL BE A DOUBLE PLAY....BUT THEY DONT HAVE TO TAG UP Just to clarify. If a fly ball is caught, the runner on 1st may try to advance, but to do so, he must be on 1st base, or return and touch 1st base, before attempting to advance. The "tag up" must take place after the ball is caught by the fielder.
Yes. A runner may tagup and attempt to advance after any fly ball is caught, regardless of whether it is fair or foul.
The runner is allowed to leave as soon as the ball touches the glove as that is the beginning of the catch.