If you serve a ball into the net, or if the ball is anywhere within 5 feet of the court I'm going to force you to pick it up, because it is a distraction. If you don't, I'll wait until you are about to hit a winner, and then call a let. That usually gets the idea across to the opponent and is well within the rules. Usually the ones who don't pick up the balls are the ones who are such a nervous wreck trying to hit a 2nd serve that they don't want to move and reset.
You can't do the bold. If you start the point with it on the court you have to finish it out.