It is proper to cover the table with a tablecloth for the Shabbat meals, as an expression of honor for Shabbat. Hacham Ovadia Yosef writes that the tablecloth does not necessarily have to be white.
It is customary on Friday night to sing "Shalom Alechem" upon returning from the synagogue. In this hymn we welcome the angels that escort us home from the synagogue on Friday night. The Gemara in Masechet Shabbat (119) writes that a person is accompanied by two angels as he walks home from the synagogue on Friday night – a good angel to his right, and a hostile angel to his left. If the house is neat and properly arranged for Shabbat, then the kind angel declares, "May it be His will that it should be this way next week, as well." The hostile angel is then compelled to respond, "Amen." If, however, the house is disorderly and not prepared for Shabbat, then the hostile angel proclaims, "May it be His will that it should be this way next week, as well," and the good angel has no choice but to answer, "Amen."
The Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in Parashat Bereshit (29), writes that the proper text of "Shalom Alechem" is "Melech Malcheh Ha’melachim…" This is as opposed to the text customarily recited by Ashkenazim, "Mi’melech Malcheh Ha’melachim…"
After singing "Shalom Alechem," one recites "Ki Malachav Yesave Lach" and "Eshet Hayil."
The bread on the table should be covered during Kiddush. Normally, when a person eats bread and wine, Halacha requires reciting the Beracha over the bread before reciting the Beracha over the wine. On Shabbat, however, one may not eat before reciting Kiddush, and we must therefore recite the Beracha over wine before reciting the Beracha over the bread. In order not to "embarrass" the bread, which is usually given precedence, we cover it while we recite Kiddush. Furthermore, the covering commemorates the Manna, the miraculous food that fell from the heavens to sustain Beneh Yisrael as they traveled in the wilderness, which was covered both on top and on the bottom. Therefore, one should ensure that the bread is covered both on top and on bottom. The tablecloth or a breadboard suffices as the bottom covering.
Hacham Ovadia Yosef (listen to audio recording for precise citation) rules that one should also cover all "Mezonot" food that is on the table during Kiddush. On weekdays, "Mezonot" food, like bread, is eaten before wine, and thus the concern for not "embarrassing" the bread during Kiddush applies to "Mezonot" food, as well. Hence, as Hacham Ovadia cites from several authorities, one should cover "Mezonot" food during Kiddush. Although the work "Az Nidberu" rules leniently in this regard, and does not require covering "Mezonot" food, it is proper to follow the stringent position. This is especially true when a person eats a breakfast on Shabbat morning consisting of only "Mezonot" food, without bread, in which case the "Mezonot" food takes the place of bread; the "Mezonot" food must be covered during Kiddush. But even on Friday night, or on Shabbat lunch, when one has bread on the table, the "Mezonot" food should also be covered. Over foods, however, such as fruits and vegetables, do not have to be covered during Kiddush.
Summary: One should cover the table with a tablecloth for the Shabbat meals. During Kiddush, one should cover the bread and "Mezonot" food on the table, on top and on bottom, though the tablecloth or breadboard suffices for the bottom cover. In the "Shalom Alechem" hymn recited on Friday night, the proper text according to Sephardic custom is "Melech Malcheh Ha’melachim," as opposed to "Mi’Melech Malcheh Ha’melachim."
