Does divorce take place if the husband says, "If I tell you we will go out at such and such an hour, and you are more than half an hour late, then you are divorced," and then he does not specify a particular hour, and the wife is more than half an hour late? And does the divorce recur with repeated breach of the oath if it occurred once?

What your husband uttered is considered a conditional divorce. If your husband did not specify a particular time after Asr, then your going out does not constitute a divorce, unless he intended a specific time and you went out more than half an hour later. Intention is given consideration in oaths; if the one swearing an oath intends something that the wording can bear, then his intention is given effect. The conditionality of divorce is dissolved by the occurrence of the condition for the first time, unless the wording indicates continuity, such as "whenever."