A runner can slide into any base.
only in little league
Whenever there is a play the runner has to slide. there is no mandatory slide rule the runner just has to avoid contact
No they dont if they dont wont to
not unless the bases are loaded, creating a force at home for the runner on third otherwise the runner must be tagged to be put out
Yes, a runner may slide into any base at any time.
Yes. A runner can slide into any base.
Assuming the catcher is near home plate, the runner has to slide. If he doesn't and knocks the catcher down he is out. If the catcher is up the baseline and is waiting to make the tag the runner would be called out for crashing into him. If the slide knocks the catcher down, the outcome of the play would depend on whether the catcher maintained control of the ball during the tag and whether the runner touched home plate.
No. That would be an obstruction and the base-runner would be safe.
Depending on your league rules. In general, the answer is yes, provided that your league has not adopted a "must slide rule".
you would have to be really far up in the box... i think the batter has to move