OK, so you are looking for the probability that the die will come up red on any given roll. Consider this a '1' for that die. Therefore, the chance that it will come up red is the same as rolling a '1' on a 12-sided die. The chance of rolling a 1 is 1 in 12.

The chance of rolling a '1' is independent of the previous rolls. The chance of decay is therefore always 1/12 for the next roll, or 11/12 that it will not decay. Since a die can only decay once, and will be 'out of play' once it does, you calculate the odds of it not decaying over a given number of turns, which for n turns would be (11/12)^n. That should let you calculate the answers for all of the questions.

Mike