None of these situations is insurmountable so long as both the lawyer and the other members of the board understand the issues. The key is acknowledging the issues before they arise, so that nobody will be surprised and neither the lawyer nor the organization will be put at risk.
A lawyer serving on the board of a nonprofit should have a serious discussion with the other members of the board about their mutual expectations for service. The lawyer may face ethical issues which could come as a surprise to everyone if not faced in advance. The lawyer and the organization should consider whether the benefits outweigh the risks of dual service.