The question about the single point, or rouge, is pretty common, but it's so controversial that it's always a good question. So, I'll do my best to give you a good answer. I'll leave the coin toss question to others because I'm not sure I understand it myself.
The single point can happen any time the kicking team, either on a field goal or a punt, kicks the ball through the (20 yard) end zone or the receiving team fails to run the ball out.
The object of this point is not to reward a team for failure, as some mistakenly believe, but to reward the kicking team for field position. Since the the end zones are so deep (they used to be 30 yards) a team actually has be fairly close to actually kick it through. For example, if the ball is on the 35 yard line, on a field goal the kicker would have to boot it about 61 yards to kick it out of the end zone (seven yards added for the snap and hold).
The rouge is fairly common, but so are returns out of the end zone. In fact, one of the most exciting plays is the return of a (missed) field goal or punt for a touch down. Already this year there was a 129-yarder. So, while still misunderstood and controversial, the rouge is an important play and often results in exciting action.
Also, Since the 1940s, a Grey Cup has never been decided because of a rouge. Though, there have been several in the Big Game.
There is a more detailed explanation of the rouge here: