Seuda shlishit: A baraita, quoted in Ta’anit 29b, says that one may eat as extravagant a meal as he wants on Shabbat, even if the ninth day of Av falls on that day or the next. The Tur[1] cites customs that one is allowed and would do best to curtail the Shabbat meal in this case. This is especially so at se’uda shlishit, which in effect is the se’uda hamafseket.[2] However, these considerations are countered by the requirement to avoid displaying mourning on Shabbat. Therefore, there are no real restrictions, even at se’uda shlishit.[3] However, the mood should somewhat reflect the coming of Tisha B’Av, as long as it does not bring on clearly noticeable changes.[4] One important halachic requirement is that one must finish eating before sunset.[5]
Havdala: One says the standard preliminary Havdala in Shemoneh Esrei. The main Havdala over a cup of wine is made on Sunday night, after Tisha B’Av.[6] Nevertheless, if one forgot to mention Havdala in Shemoneh Esrei, he does not repeat Shemoneh Esrei. Rather, saying HaMavdil, which enables one to do actions that are forbidden on Shabbat, suffices.[7] Unlike Havdala during the Nine Days, when we try to have a child, rather than an adult, drink the wine,[8] after Tisha B’Av an adult can drink it freely.[9] The beracha on besamim[10] is not recited this week because it is said only on Motzaei Shabbat, and on Tisha B’Av it is not appropriate because it is supposed to serve as a pleasure that revives the soul.
The beracha on the fire is also specific to Motzaei Shabbat, but it is not connected to a pleasure and does not require a cup of wine. Therefore, the minhag is to recite it in shul toward the end of davening, before the reading of Eicha.[11] There are those who say that a woman should, in general, avoid making Havdala. This is because of the doubt whether a woman is obligated in the beracha on the fire, which is not directly related to Shabbat, and thus is a regular time-related mitzva, from which women are exempt.[12] Therefore, if one’s wife will not be in shul at the time of the beracha, it is better for the husband not to fulfill the mitzva at that time, but to make the beracha on the fire at a time that his wife can hear it.[13]
Taking off shoes: As we mentioned, one may not do a noticeable act of mourning before Shabbat is over. Whereas finishing eating before sunset or refraining from washing need not be noticeable, taking off shoes is. There are two minhagim concerning when to take them off: 1) One waits until after Shabbat is over, says HaMavdil, and then changes clothes and goes to shul. One may do so a little earlier than the regular time listed for the end of Shabbat, which is usually delayed a little bit beyond nightfall to allow for an extension of Shabbat at its conclusion. The exact amount of time is not clear and depends on the latitude of one’s location. It is advisable to delay Ma’ariv to allow those who take this approach ample time to make it to shul.[14] (If the rabbi has ruled that everyone should keep the following minhag, all should conform, and there is no need for such a delay.) 2) One takes off his shoes after Barchu of Ma’ariv. One who takes the second approach should bring non-leather footwear and Eicha/Kinot books to shul before Shabbat to avoid the problem of hachana.[15] However, if one makes even minimal use of these sefarim in shul before Shabbat is over, he may bring them with him on Shabbat.[16]