Yes, you should always report previous charges, even if you do not think they are applicable. Not reporting is withholding information.

First of all, it would depend on what government you were jailed by.If the government was more along the lines of North Korea, Syria, or any other non democratic government, who would just look for any reason to jail you, I would say it would not matter. It sounds like it can be logically explained to your employer.

I think you should report your crimes, if not it is withholding information giving them a right to fire you on the spot if someone finds out and brings it to the attention of the schoolboard. Even if it were not a severe offense it is up to the school to decide.

I don't think these past charges are anyone's business, especially if they are far enough in the past. I don't like how modern society judges people all their lives for mistakes that people make when they are young. While I think honesty is always best, I imagine being forthright with this will prevent you from being hired. I think anyone who is not "subversive" in any way, does not have their priorities in the proper place. I myself have been jailed for subversive activities. I don't think I will bring it up in an interview.