The Three Weeks

1. The night before shiva Asar B’Tamuz one is permitted to eat or drink until the morning or daybreak which is usually 72 minutes before sunrise. However if one sleeps a normal nights sleep, he should really stipulate before going to sleep that he will eat or drink or both when he awakens otherwise it is a question if he may eat or drink although it is before daybreak.
2. The laws of the three weeks take effect already at night. The Shulchan Aruch is of the opinion one should avoid reciting the brocha of shehechayanu during these days on new fruits, clothing etc. The Mishna Brura concludes that on Shabbos one need not refrain from saying this brocha.
3. Although our custom is not to make weddings during this time, however an engagement party, a tinaim, would be permitted even with a meal.
4. From shiva asar B’Tamuz when they broke throught the walls of the city of Yerushalyim until they destroyed our holy Bais HaMikdash three weeks later, is time for retrospection on the destruction and why the destruction. Therefore it is inappropriate to listen to music or engage in frivolous activities during this time.
5. Although there is no prohibition of conducting ones business or going to work during the three weeks before rosh chodesh, however the Biur Halacha suggests that on shiva asar B’Tamuz one should try to concentrate on the taanis and minimize his work.
6. One may certainly purchase and wear new clothing that do not require a shehechayanu, until rosh chodesh av.
7. If one ate unintentionally on the taanis, he still continues to fast and completes the taanis. Pregnant and nursing women who are able to, at least, attempt to fast, should do so. All those who eat on taanis because of reason of health etc. or small children, should not eat heavy or fancy meals but just the minimum type of meal.
8. Some have a stringency not to take a hot shower even on the other three regular taanis tzibur, of which one is shiva asar B’Tamuz.
9. The additions in davening are:
a) The chazan adds anenu as a separate brocha, shacharis & mincha.
b) Slichos and avinu malkenu at shacharis.
c) Krias HaTora - vayichal at shacharis and mincha.
d) Haftora at mincha.
e) Each person says anenu at mincha as part of shomea tfila.
f) The Chazan says bircas koanim and all say sim shalom in shmone esrei.
g) Avinu malkenu
10. Although it is a taanis tzibur the Mishna Brura says that one who is not fasting should not say anenu.
11. If one davens together with the repetition of shmone esrei he does not say anenu as a separate brocha.