What happens to changes made by the president of the United States after her/his impeachment? Will executive orders and such automatically be invalidated, put on hold upon revaluation, revaluated, ...?
Executive orders stay in place until they are revoked or changed by the new President (the former Vice President). The new President can do that as easily as the precedessor made them. But only if the new President wants to do that. Laws not vetoed by the last President stay valid until Congress makes new laws which revoke them, and they are under no obligation to do that. Any officials appointed by the last President stay in office until the new President replaces them (if they can be replaced - Supreme Court justices, for example, are appointed for life and thus will keep their positions).