May be differences in supplements but...
-First of all I believe it is in a 9 month period, not a full year. Discipline falls off after 9 months.
-Had my BA tell me little violations, even little accidents can never get you permanently fired no matter how many. Even if you have a serious accident the little ones before hand do not determine if the termination sticks for the big one. We had one guy with 5 avoidables in 9 months...His termination did not stick.
-They will try to pressure you. If you have an unreported accident and don't get caught they win because it is one less on them. If you do get caught, they win because they can fire you. REPORT all accidents! You won't loose your job that way unless it is a serious accident.
-I have never heard of this BS (3 safety violations automatically going anywhere)
When you say local level hearing are you just talking about a single warning letter hearing with your steward? They can try to give you a warning letter for anything. Just grieve it.