Day Questions

Is it permissible for a person who is not a mujtahid to teach from books like Usool al-Kafi and Bihar al-Anwar?

It is not permissible to inform about religious issues without knowledge, whether such information is in on religious jurisprudence or beliefs. Yes, it is permissible to search and study the religious sciences and learn about the narrations of the Ahlulbait and other related material.

If temporary marriage was contracted for a week with a woman who was a traveler, and she travelled away the next day without notice, must her dowry be paid in full?

If he asked her to be with him during the duration of the marriage and she refused, or he has previously stipulated this on her and she refused to act upon this, he is not liable to pay that portion of the dowry in proportion to the percentage of the time she was unavailable.

If a person talked to me privately and it was understood that he didn't want me to tell others of those matters, will it be sinful for me to tell others?

If he stipulated upon you a condition that you do not reveal this information, then it is not permissible to so. If he wants you not to mention it, then it is better to keep the trust between you too.