The two I failed on were not what I'd call rules (or even laws).
They were to do with the referee's hand signals (in my day referees had tongues) and the current practice of having hookers delivering the ball at line-outs (which is more to do with technical fashions in play - it used to be the winger's job, because the point of a line-out was to achieve options for running the ball).
Anyone can take a lineout, as has been said before wingers used to do it.
The scrum is not limited to 8 men, if you wish you can 15 men involved providing you are not putting the ball in, if you were then you can only have 14 men.