>"Walk him"? You mean let him walk to 1st base - give away a run - so he doesn't get a homer?

Yep and prevent him to advance the runner on 2nd base. That strategy is usualy used when the next batter pose less at threat than the one presently at bat (specially if the next batter is the pitcher).

>>2. If there is a runner on 2nd and nobody on 1st, the pitcher might do this in order to set up a force at 3rd base.
>
>"Set up a force"?

Without a runner on first base, the runner on 2nd base isn't forced to go to the 3rd base if the batter hit the ball. He will stay on 2nd if he think he might get retired if he go to the 3rd base. If there is a runner on first, he will be forced to run when the batter hit the ball (except if it's a fly ball). That increase the chance of the defense of having a double-play (retiring 2 players on the base).

>Oh, and one more thing: The commentators refer to the situation as, say, "1 and 2", the TV dirsplay showing "1-2". Now I understand the 2nd no. to be the no. of strikes but what's the 1st? No. of good balls?

First number is the number of balls (ball thrown not in the strike zone) and second is the number of strikes.

>How does this increment?

On each throw, except if the batter have 2 strikes and he hit a foul ball.

>How high can it go? (No. of good "balls" that the batter hasn't had a swipe at? Therefore he's allowed 3?)

4 balls and he go the the first base. 3 strikes and he's out.

>The batter is allowed only 3 swipes at the ball. Is there a limit to the no. of duff pitches that can be made?

No limit on the amount of foul ball he can hit. Often the batter will intentionnaly hit a foul ball when he have 2 strikes against him to get the pitch he want.