do base runners have to go back and touch base every pitch, or do they just do that?

Technically, the baserunner is not required to return to the base after every pitch (unless it's a foul ball or a fly ball) - after a strike or a ball the runner can do as he pleases.

However, the reason baserunners as taught to tag up is that pitchers can act deceptively as long as they aren't standing on the pitcher's rubber. Rule 8.05(i) prohibits pitchers from standing in a set or windup position, or standing "Astride" the rubber, without having the ball.

So after the pitch is delivered and the ball is returned to the pitcher, the runner is at risk of being tricked into being tagged out... until the pitcher reassumes his pitching stance. As long as he's not on the mound, anyone on the opposing team might be holding the ball. Maybe the first baseman got it when you weren't looking, so if you step off the base... BAM! You're out. Once the pitcher gets ready to pitch, however, the runner is no longer at risk; the pitcher MUST have the ball, or else it's a balk; the ball is dead, and the runner advances one base.

If you watch major league runners, they will commence their leadoff only when the pitcher gets back up on the mound. All players are taught to get back on the base between pitches; that's how you avoid the hidden ball trick. Don't lead off until the pitcher's back in the set or windup position, and you'll be safe.

Lonesome Rhodes is correct.

Its not required by rule. But most players do it because its good strategy. You aren't going to take off running for the next base when the catcher, pitcher or another infielder has the ball so being 10 feet closer doesn't gain any advantage it just puts you at risk of being picked off.

When the pitcher is off the mound he can do *almost* anything to trick the runner. Once he steps on the rubber he is restricted by the balk rules which provide some protection for the runner.

They just do that. When they're on the base, they can relax as they cannot be put out. Anytime they're not on that base, they can be picked off.

Yes

If they don't they are out

Yes they do.

Never really thought about that

no, that is just little league rules. they do it so they don't get picked off