Failing to Retouch after Foul Ball


It is generally believed that on an uncaught foul ball, runners cannot not advance and they must return to retouch their original bases. 
 
A. Is this only true for uncaught fouls, or also in other dead ball situations (such as HBP, umpire called time, etc)?
 
Call
This is true in all dead ball situations, except ones where runners are awarded further bases (ball out of play, dead ball balks, etc.).


B. If the runners do not return to retouch after a foul ball, is there a penalty? If so, what is it?

Call
The umpire should not put the ball in play again until the runners have retouched their bases. There is no penalty against the runner if the umpire makes the ball live before they have retouched. However, most umpires do not enforce this rule strictly -- as long as the runners return to the vicinity of the base so as not to gain a significant advantage when the ball is put back in play, the umpire can reasonably make the ball live again.